sounds dull but you ve got to stop thinking unnecesarily.. just focus on the good things, and if things go bad, just try to force yourself to stay in the game
"let's focus on holding serve.." for example.. just limit yourself to one thing..
you just got to start thinking you can win.. even the top 1 player
just try to see the good stuff and forget about the bad stuff, just focus on success and not on failure.. hold on to the scoreboard when you re winning and forget about it when you re losing.. if you get bvroken, remember it is only 1 break, you can always come back from a break.. if you had trouble with your serve and manage to go through..turn it into something to make you stronger..
if you got broken, just think you were close enough.. and so on.. you just gotta stay in a winning mentality.. and make all doubts and loser's thoughts go away..
if you dont believe you re capable of winning even when you re down, you wont win