I have pulled a muscle in the area between bicep and tricep.?

My arm is tight and it feels like i have pulled something. There is some pain but not much. I play tennis and I have a big match tomorrow. I think that I pulled it during my last match. I usually hit my serve hard but the last set of the match where I think I pulled it, it hurt to hit my first serve. I don't know how to put a lot of spin on it so that is out of the question. If i hit my serve like I did, then I will be creamed tomorrow. Can someone help me out? Should I put heat or ice on it? Other advice?