Pros..and all opponents are not permitted to climb up on the table when you are shooting so you can NEVER compete against an opponent...only against the balls on the table.
I know it's hard not to be intimidated and to isolate during a match against any player...and especailly a better one who will probably punish you when you miss.
But your GOAL is to forget about everything else in the world and especially your opponent when you are at the table.
Being able to isolate is a trait universal to all great champions. A few weeks ago I watched a TV match between Efren and Mika where they had to call the 9 Ball. BOTH players failed to call the 9 in spite of the fact that fans were YELLING at them to do so when they were bent over their shots.
They simply paid NO attention. It was AMAZING that it would happen to both players in the same match....but it did.
I'm serious as a heart attack when I suggest you get a friend to harrass the hell out of you when you are over some fairly easy shots...say 2 diamonds between CB and OB and OB to pocket with a 10 deg. cut angle.
Have them walk around the table when you're shooting...stand RIGHT behind you and clap their hands...anything crazy to distract you.
My pal bobby pickle used to wave his hand up and down 6 inches in front of my eyes during my warm-up strokes! If you can overcome that kind of distraction, you will eventually care a LOT less about whose butt's in the chair and a LOT more about committing to the shot.
Regards,
Jim