The match-start boundary separates most walkovers from retirements, but the appointed ruleset decides the label.

The governing rules and versions used here

The main classification on this page comes from the ATP Official Rulebook 2026, especially Exhibit K, because that glossary expressly separates “Retired,” “Walkover,” “Default,” “Unplayed,” “Incomplete,” “Abandoned” and “Weather.” The ATP rulebook page and its April 2026 change notice were checked for the current 2026 version.

Where procedure or consequences differ, the page names the 2026 ITF Men's and Women's World Tennis Tour Regulations, the 2026 ITF Duties and Procedures for Officials, the 2026 WTA Official Rulebook as of 27 July 2026, or the 2026 Official Grand Slam Rule Book. The ITF Rules of Tennis govern how points are played; these draw-result labels and financial consequences sit mainly in competition regulations and codes.

How to classify an unfinished or unplayed match

1. Name the competition and edition. Do not transfer an ATP result code automatically to a WTA, ITF, Grand Slam, USTA, NCAA, school or local league event.
2. Check for a permitted replacement. A lucky loser or alternate inserted before play means the original opponent's withdrawal does not give the remaining player a walkover against that replacement.
3. Apply that ruleset's match-start test. ATP's 2026 glossary uses whether the first serve was struck, not whether a full point or game was completed.
4. Identify why play cannot occur or continue. Illness or injury, a Code sanction, an eligibility decision, weather and tournament cancellation are not the same cause.
5. Decide whether there is a winner and loser. A retirement, walkover or default normally advances an opponent; ATP “Unplayed,” “Incomplete,” “Abandoned” and “Weather” statuses can have no winner or loser.
6. Apply separate consequences. Ranking points, prize money, statistics, later draws and discipline come from the appointed competition's regulations, not from the three-letter result marker alone.

The three results answer different questions

• Retired: under ATP Exhibit K, the losing player retired because of illness or injury after the match began.
• Walkover: the match did not begin because the losing player was ill or injured, was penalised before the first serve, or was otherwise not permitted by ATP or the Supervisor to play. The label is not used if a lucky loser or alternate replaces that player.
• Default: the losing player was defaulted under the Code of Conduct after the match began.

This exposes the flaw in the shortcut “medical means retirement; misconduct means default.” Timing also matters. Under ATP terminology, a disciplinary bar imposed before the first serve can lead to a walkover rather than a recorded default result.

The first serve can matter more than the first completed point

ATP Exhibit K places a pre-match Code penalty on the walkover side of the line when it occurs before the first serve is struck. Its retirement and default definitions apply after the match has begun. The practical boundary is therefore not “at least one point was played.”

If the server strikes a first-serve fault and then becomes unable to continue before the second serve, the match has begun under that wording even though no point has been completed. By contrast, an injury during the warm-up occurs before the first serve and can lead to a walkover if no replacement is made.

A withdrawal creates a vacancy; it does not always create a walkover

“Withdrawal” describes the player leaving a draw or event. “Walkover” describes the awarded match result when the opponent does not have to play. If the regulations allow a lucky loser or alternate to fill the vacancy, the scheduled player changes and there is no walkover against the replacement.

If nobody replaces the unavailable player and the competition awards the match, the advancing opponent wins without an on-court score. ATP's glossary also recognises “Unplayed” for a match that did not begin for a reason outside its specified walkover grounds; that status has no winner or loser.

A retirement is final for that match, not a suspension

An injury stoppage, medical evaluation or weather delay does not by itself create a retirement. Play can resume after an authorised interruption. A retirement is recorded when a match that began is ended because the losing player cannot continue for the medical reason recognised by the governing regulations; the opponent advances and the score reached on court remains part of the match record.

A suspended match is different: the same match is expected to resume. ATP separately uses “Incomplete” when resumption is anticipated, “Weather” when inclement weather caused that status, and “Abandoned” when a begun match will not be completed for a reason other than retirement or default and there is no winner or loser.

Treatment time and a retirement are separate decisions

Under the 2026 ITF Duties and Procedures for Officials, a Sports Physiotherapist must evaluate the player before an authorised Medical Time-Out. Treatment is normally limited to three minutes and to one Medical Time-Out for each distinct treatable condition. At non-professional events and professional M15, M25, W15 and W35 events, the Supervisor or Referee may extend the treatment time if necessary.

Muscle cramping is a specific boundary case: it may be treated only during changeovers or set breaks and does not receive a Medical Time-Out. A severely cramping player may forfeit the points or games needed to reach a changeover or set break for treatment. If the player can legally resume, the match continues; if the match is ended for the medical condition after it began, the result is a retirement under the applicable tour classification.

The WTA requires more than a scoreboard label

Section IV.B of the 2026 WTA Official Rulebook, current as of 27 July 2026, requires a player who retires to call for the Primary Health Care Provider and Supervisor before retiring and give the reason. Immediately afterward, the player must undergo the required medical evaluation, complete the medical information and withdrawal forms, and provide the required public statement.

Those administrative steps do not change who won the unfinished match, but they show why a broadcast marker is not the whole ruling. The governing tour may require medical evidence, forms and follow-up before it settles later eligibility, fines or compensation.

A default can follow escalation or one severe act

For the ITF World Tennis Tour in 2026, the ordinary Point Penalty Schedule is warning, point penalty, then game penalty for the third and each later offence. After the third Code Violation, the Supervisor decides whether a subsequent violation is a default. The Supervisor may also declare an immediate default for a single Code violation.

The 2026 ITF Duties and Procedures for Officials says bypassing the schedule is a serious step reserved for severe and flagrant misconduct. The Chair Umpire announces lower Code penalties and calls the Supervisor or Referee to discuss a possible default; the Supervisor or Referee makes the default decision. A player can therefore be defaulted while leading, and prior warnings are not required for a sufficiently serious act.

“Defaulted” as a sanction may not be the public result label

The 2026 ITF World Tennis Tour Code says a player not ready within 15 minutes after the match is called shall be defaulted unless the Supervisor, after considering the circumstances, elects not to do so. It also permits an immediate default for failure to obey a direction to change unacceptable attire or equipment.

That disciplinary decision and the draw notation must still be read under the competition's result rules. ATP makes the distinction explicit: if a player is subjected to a Code penalty before the first serve, the advancing opponent's result is a walkover. This is why “default” can describe what officials did to one player while “W/O” describes how the unstarted match appears in the draw.

Points and prize money do not follow one universal formula

• ATP 2026: Exhibit K says winners of walkover or “no match” matches receive points and prize money as if the match had been played. Separate financial rules govern compensation for the player who withdrew.
• ITF World Tennis Tour 2026: a first-round walkover recipient, or a later-round recipient who has not yet played, receives prize money for the round but no ranking points. A later walkover after the player has already played and won a match carries the points and prize money for the round reached.
• ITF World Tennis Tour 2026: a defaulted player normally loses the points, prize money and hospitality earned in that event, subject to stated exceptions for punctuality, dress and equipment, a medical-condition default, and an innocent doubles partner.
• WTA 2026: a walkover recipient receives prize money for the round reached. For a disciplinary default after the match begins, the advancing player receives prize money for the round and the defaulting player loses the prize money and ranking points earned in that event, subject to the doubles-partner provision.
• Grand Slam 2026: an eligible on-site medical withdrawal before a first singles match can receive 50% of first-round prize money under the conditions in Tournament Regulations J.1, while a lucky loser or alternate can take the vacated place. That is a withdrawal-and-replacement rule, not proof that every such situation becomes a walkover.

A singles retirement does not automatically erase doubles

Each draw has its own commitment and medical rules. Under WTA Rule IV.C.2 for the version current on 27 July 2026, a player who withdraws or retires from singles may still play doubles when the rule's scheduling and medical conditions are met. For a doubles match scheduled on the same day, the Tournament Physician must not have declared the player unfit.

The result still ends the retired singles match; it does not prove that the player is medically barred from every later match. Conversely, a tournament physician's unfit finding or a Code decision may require withdrawal or removal from other draws. Check the regulation for that event rather than inferring fitness from the abbreviation “RET.”

An ankle injury occurs during the warm-up

Situation: the scheduled player completes part of the warm-up but cannot start. No first serve is struck, and no lucky loser or alternate replaces the player.

Ruling: walkover under ATP Exhibit K. The decisive fact is that the match did not begin; taking part in the warm-up is not the glossary's match-start test.

The first serve is a fault, then the server cannot continue

Situation: the server strikes a fault on the opening point and immediately aggravates an injury before attempting the second serve.

Ruling: retirement if the player ends the match because of that injury. The first serve was struck, so the match began even though no point was completed.

Serious misconduct occurs after play begins

Situation: during the second set, a player commits a severe Code violation and the authorised official removes that player under the Code.

Ruling: default. Under ATP Exhibit K, the key facts are that the match had begun and the loss resulted from the Code, not illness or injury. The score before the incident does not protect the offending player.

A player is 16 minutes late after the match is called

Situation: the player is not ready within 15 minutes and asks to play anyway.

Ruling: Article IV.B of the ITF World Tennis Tour Code directs a default unless the Supervisor, after considering all relevant circumstances, elects not to declare one. The 15-minute threshold creates the default power, but the stated discretion means the outcome is not automatic in every fact pattern.

A player retires from singles but has doubles later

Situation: the player follows the WTA retirement procedure and asks whether the singles result automatically removes her from doubles.

Ruling: not automatically. WTA Rule IV.C.2 applies its scheduling and medical tests; if the doubles match is on the same day, the Tournament Physician must not have declared her unfit. The singles retirement ends that singles match, while eligibility for doubles is a separate decision.

Five shortcuts that produce the wrong answer

• “One point must be completed before it is a retirement.” ATP uses the first serve as the relevant boundary; a completed point is unnecessary.
• “Misconduct always appears as DEF.” ATP can record a walkover when the Code prevents play before the first serve.
• “Withdrawal and walkover mean the same thing.” A replacement may fill the vacancy, so no opponent receives a walkover.
• “A default always requires warning, point and game penalties first.” ITF procedure permits an immediate default for severe and flagrant misconduct.
• “The result marker settles points, money and later eligibility everywhere.” ATP, WTA, ITF World Tennis Tour and Grand Slam regulations apply different consequence rules.

Governing-body sources and effective versions

• ATP — 2026 Official Rulebook, Exhibit K “Glossary” and draw-result definitions; current file incorporating April 2026 changes
• ATP — Changes to the Published 2026 Official Rulebook, current revision 27 April 2026
• International Tennis Federation — 2026 Men's and Women's ITF World Tennis Tour Regulations, Sections XII and Code of Conduct Article IV
• International Tennis Federation — 2026 Duties and Procedures for Officials, Medical Rule and Immediate Default procedure
• WTA — 2026 Official Rulebook as of 27 July 2026, Sections IV.B–C, VII.I and IX.C
• Grand Slam Tennis — 2026 Official Grand Slam Rule Book, Tournament Regulations J.1 and Code of Conduct

Checked on 28 August 2026 against the official 2026 ATP, WTA, ITF World Tennis Tour, ITF officiating and Grand Slam documents linked above. ATP terminology supplies the main result-classification baseline; competition-specific regulations supplement or alter the procedure, replacement rules, points, prize money and later eligibility. National associations, college bodies, team competitions and local events are outside this page's primary scope.