i am exercising all my personal restraint not to be crude.
i wouldn't recommend getting him anything to do with tennis, unless you know lots about the sport AND know all his personal preferences as far as raquets, shoes, etc. -- tennis is extremely delicate to most serious players. 'cept that virua-tennis game idea; that was a good'un.
try and think of something that will be uniquely from you, in that noone else would know to give it to him (or be able to). that's definitely a tricky criteria, but since you're trying to sway his feelings your way, i'd say that's pretty important... like organize a suprise party, but be the one that lures him in (so it's clearly your thang).
if all else fails, give one of my cruder suggestions a try -- they are lurking in my mind, struggling to get out, but i'm sure you can guess the most effective ones.
==D - -- ;
oops that one got away from me!