Retirements, walkovers, and defaults are different ways a tennis match can end or not start.

How officials classify it

1. Confirm whether the match officially started. In practice, that means the first point began under the match procedure being used.
2. If play started and a player or team cannot continue because of injury, illness, or another non-disciplinary reason, record a retirement.
3. If play did not start because a player or team could not appear or was withdrawn from that match, record a walkover unless the event rules require another classification.
4. If the player is removed for conduct, refusal to play, ineligibility, or a serious rule breach, treat it as a default.
5. Apply the competition's separate rules for score notation, prize money, ranking points, lucky losers, doubles substitutions, and disciplinary follow-up.

A retirement happens after the match has started

A retirement means the match was underway and one player or team stopped before completion. The most common reason is injury or illness, but the important rule distinction is timing: once the match has begun, the opponent does not receive a walkover. The opponent wins the match by retirement and the score is normally shown up to the point where play stopped.

A walkover means the match is not played

A walkover is used when a scheduled opponent does not start the match. That can happen because of injury, illness, personal circumstances, travel problems, withdrawal after the draw, or another accepted reason under the tournament rules. The advancing player or team moves on without winning points, games, or sets on court.

A default is a penalty or disqualification

A default is different from being unable to continue for ordinary medical reasons. It is used when the rules require a player or team to be removed or lose the match because of misconduct, a serious code violation, refusal to play, failure to comply with officials, ineligibility, or another disqualifying breach. In higher-level events, a chair umpire may identify the problem, but the referee or supervisor is usually involved before a default is confirmed.

The start of the match matters

The cleanest practical distinction is whether the match started. If a player withdraws before the first point, the result is usually a walkover. If the same player plays one point and then cannot continue, the result is usually a retirement. This is why scoreboards and draws may show very different labels even when both situations come from the same injury.

How the result is recorded

• Retirement: the completed score is shown up to the stopping point, followed by a retirement marker such as "ret." or the event's equivalent notation.
• Walkover: no match score is created because no points were played. Draws commonly mark the advancing player with "walkover" or "w/o".
• Default: the opponent is awarded the match, and the record may note "default" or "def." depending on the competition's system.
• Doubles: the same concepts apply to teams. If one partner cannot continue after the match starts, the team normally cannot continue unless the competition has a specific replacement rule before play begins.

A medical problem is not automatically a retirement

A player may receive evaluation or treatment only within the limits allowed by the event rules. If the player can resume in time, the match continues. If the player cannot resume, or chooses not to continue, the match is ended by retirement. Ordinary fatigue, loss of form, or tactical discomfort does not create unlimited treatment time.

Defaults are about rule breaches, not just the score

A player can be defaulted even while leading, and a player can win by default without winning the final point. Serious abuse of an official, dangerous conduct, deliberate failure to play, or repeated code violations can trigger default procedures. The exact penalty ladder and who must approve the default depend on the governing body and event regulations.

"A walkover and a retirement are the same"

They both advance the opponent, but they are not the same result. A retirement is a match that began and then ended early. A walkover is a scheduled match that did not begin. That difference can affect statistics, head-to-head treatment, betting settlement, ranking or prize rules, and tournament administration, all of which are handled by the applicable event rules.

"A default only happens after warnings"

Many code systems escalate through warning, point penalty, game penalty, and then default, but serious conduct can be punished more quickly. An official does not have to ignore dangerous or extreme behaviour just because the player has not already received lesser penalties in that match.

How similar situations are labelled

• Player injures an ankle during the second set and stops: retirement, because the match had started.
• Player withdraws an hour before the match because of illness: usually walkover, because no point of that match was played.
• Player refuses to resume after being instructed to play: may become a default or other disciplinary result, depending on the event procedure.
• Player commits a serious act of misconduct after losing a point: the match can end by default even though the last rally was already over.

Source material

• ITF Rules and Regulations
• ITF Rules of Tennis
• ATP Official Rulebook
• WTA Rules
• USTA Friend at Court