Oh, yes. The Stare of Champions. I remember it well. When I was a kid, I played tennis for over ten years, seriously/obsessively. My best tennis coach was a hard assed bastard, and trained me to hate that ball, ya gotta wanna KILL that fucking ball!
This is a more effective learning tool than the old saw, "Keep your eye on the ball". That sounds, and is, boring. That does not focus your undivided concentration the way that pretending (til you reflexively believe it) that the ball is an enemy, a threat, evil and it must be killed with your racket if you are to survive (win the match).