If a player withdraws during the first set of a match, then the bet will be void. However, if the player retires from a match after the completion of the first set, we will base the settlement of your bet on tournament progression.
For example, you have placed a bet on Nadal to beat Murray at Wimbledon. Nadal retires due to injury in the 3rd game of the second set. Your bet will be classed as a loss as Murray progresses to the next round.