In the event of any of the following circumstances all bets will stand:

A change of schedule and/or day of match
A change of venue
A change from indoor court to outdoor court or vice versa
A change of surface (either before or during a match)

Outright Betting
Non-runner no-bet.

Match Betting Including In-Play
In the event of a match starting but not being completed then all bets will be void unless after the start of the match a player is disqualified in which case the player/team progressing to the next round or being awarded the victory will be deemed the winner for settlement purposes.

Tournament Match Betting
Both players in a specified match-up must play 1 point in the tournament for bets to stand. If players progress to the same round of the tournament bets will be void.

A tennis match is deemed to have commenced with the first serve and the player who progresses to the next round or wins the tournament if in a final, will be deemed the winner.  However, if a match is a walkover or ends prematurely for any reason, all single match bets thereon shall be void and multiples will be recalculated excluding that leg. Any player withdrawing from the tournament, after starting, by way of walkover, disqualification, illness or injury or any other reason shall be a loser in the outright market.

Any bet placed after the start of a particular match shall be void and where included in a multiple, the remainder of a bet will stand and the odds adjusted accordingly.

Bets stand regardless of any change of venue or court surface.

For set betting, if the match does not start or is unfinished due to either players’ incapacity or disqualification, the bets shall be void.

In the event of a change in the total number of sets played, match bets will stand but set betting shall be void.
Markets Based on Total Games/Handicap Games Including In-Play
These general rules apply to Games in Individual Sets, Games in Match, Player Games, and Handicap Betting (based on games won). 
In the event of forfeited points/games, these will count for final settlement.
For the purposes of all such markets a tie-break or Match tie-break is counted as one game.

In the event of retirement, disqualification or change of surface mid-match, bets will be void unless there is no conceivable way the set and/or match could be played to its natural conclusion without unconditionally determining the result of that market.