How many balls...

[magicmerlin]

constitute a set at wimbledon when the umpire calls 'New Balls Please'?

[osprey]

New balls are distributed, and the old ones discarded and not used again, after every 9 games except in the first set where they are changed after 7 games - the reason being that the balls have been used when the players are warming up.

[magicmerlin]

Thank you Osprey, I knew that already.

If you read the question again you will see that I asked 'How many balls etc' not 'how many sets of balls'.

As it happens whilst watching a match during wimbledon I noticed 2 packs of 3 being emptied when new balls were requested.