j87w

I was at the track the other nite and was running my car. My 3rd never grinds or anything. Out of no where it started not going into 3rd. Like itll go in at low rpms and at high if you push in the clutch and wait a sec then itll go. My clutch master cylinder is leaking and im going to replace it. It acts as if there is a wall there and it just wont go. I tried to shove it and it still wont. So now I just shift "slow" into 3rd when im racing. Any ideas why it would do that. Also it doesnt grind when it finally goes in.

Thanks