What happens if a player retires during match?

Perhaps you might like to read the 'rules' wording next to where you place your bet on the tennis - it clearly explains it.

thanks for pointing me in the right direction, One last question, how do you work out the amount of commission befair take?

http://learning.betfair.com/en/

just above the Lay Prices on any market you open you will see 'More Options'Click on that and then tick the boxes Display P&L net of commission and Display "what if" figureThen you will be able to see exactly how much you will get paid on a bet after

Thanks again for the replies. Any of you two into tennis i'm thinking of having almagro/Isner double 2morro and just wanted to know what you think.

No soorry , hardly watched a match since McEnroe retired.There is a Tennis Forum, though it is full of loonies.

I know, i've posted the same there and got no answers.