it looks like your insecure, when you get to the game and warmup, first thing you do is yell, (PASS, SHOT, or LETS GO!!!!!!!!), do it like 3 or 4 times and you will get outgoing automatically, and relaxed to talk to your teammates.
After that make sure your warmed up real good, so try a few tricks or juggle before the game to get your touch smooth, get a lot of touches on the ball in the warm up.
When the game starts, yell again ( MAN ON!!, TURN LEFT!!) and talk a lot , you will then stop thinking about it and just do it.
Then tell yourself, you cant afford to play like you did previosly, and that you need to play for your fullest, or all the practice and effort would be for nothing!!!!!!
You have two options, to be the intimadated, or the intimidator, seize the moment, squeeze it and hold it, then freeze it..