While rallying yesterday I received a very hard hit shot that was headed to land a few feet out. Hugging the baseline, I tried to drive-volley it back with my right-side forehand but apparently I made contact way off-center. The impact caused a stinging pain to the big knuckle of my index finger -- not from impact against the knuckle but from lateral pressure against my index finger tearing it downwards (perhaps the ball came down against the top of the frame). I thought I could shake it off, but the sensitivity persisted. For the rest of the session, I could sort of slice the ball but I had no strength to support the racket head to hit topspin. After a little while I resorted to hitting two-handed on that side. (I use one of those two-handled rackets and normally hit one-handed forehands left and right.) Today, I really cannot say for sure that I see any swelling, nor do I see any black-and-blue. The finger is fine for typing, and there is no discomfort as long as the finger is relaxed. Nor does it hurt much at all to wiggle it around. But over the past twelve hours the range of comfortable motion has gradually decreased, and it hurts if I try to use that finger for any activity requiring a firm grip. Any ideas as to exactly what I likely strained, whether it is likely to correct itself with time and rest, and if so, how much time and rest it will take? I think I may have had a much milder case of this six months ago when practicing serve returns with someone who served much harder than anyone I previously hit with, and miss-hit a few. But that resulted only in a bit of soreness that went away in time; it did not actually prevent me from using the hand. Has anyone else experienced this kind of "tennis finger"?