I've had patellar tendonitis for 2 years (have yet to fully recover) and I've basically lost my serve, in the meantime. I'm now serving like Coria...can't get it into court, and have totally lost confidence in my knees and my ability (or lack of it) to get any serves in.
2nd serves. I have a decent kick serve but it just sits there and my opponent can easily take advantage if he sees it, so I try to mix up my second serves throwing in slices and some flats, but it drops my 2nd serve percentage. The worst is when I need the 2nd serve to stay in a game/set/match.
Smash - mediocre at best. I can't put them away with much power - bizarre since I have a relatively big serve, so I tend to just slice them into the space now. Annoys the hell out of my opponents who think I'm playing safe, but seriously, it's all I can do!
Backhand drive - similar to a number of posters here, I have an inconsistent single-hander. Great for passing shots, even better than my forehand...but useless in a baseline rally where I more often than not mis-time it if I go for it. Thank god I have a good slice!
1)Forehand on high topspin balls,when I dont have time to take them before they jump too high.
2)Balls that are coming to slow and I begin to think a lot how should I hit it or where should I put it If it comes fast I have no problem as I dont have time to think.