Anyway,here is some article,perhaps it is better explained here:
Frustration factor sends Haas to defeat against Simon
INDIANAPOLIS, Indiana (AFP) — Frenchman Gilles Simon preyed on the frustration factor of Tommy Haas in a 4-6, 6-4, 6-2 defeat of the German to reach the semi-finals of the Indianapolis Tennis Championships on Friday.
Simon, who won his third career ATP title in Casablanca last May, next faces the huge serve of American fourth seed Sam Querrey, who hammered 17 aces in a 6-1, 3-6, 6-3 victory over compatriot Bobby Reynolds.
Haas, seeded fifth, won the opening set in steamy temperatures but lost his way in the second as he went down a break in the ninth game, 4-5.
After dropping the second set, the former number two was handed a rare point penalty for the most innocuous of offences - a racket smash and a minor swear - by umpire Fergus Murphy in the second game of the third.
That incident appeared to break Haas's will and open the door for Simon, who is now one victory away from becoming the first French finalist in Indianapolis since Olivier Delaitre in 1994.
"Today was my best match of the week," said Simon, ranked 25th in the world. "My serve improved and at some important points I hit aces.
"I could tell Tommy was getting frustrated,and I tried from the second set to hit the ball harder. I feel my game is coming along."
Haas admitted his emotions rose to the surface at the wrong moment.
"I went up a decent 3-1 in the second, then he broke me back at 4-5," said the 30-year-old, who was playing in his first quarter-final since March when he withdrew against Roger Federer with a sinus infection.
"My confidence and motivation suffered when I got broken back. I was struggling to finish points and lost come focus on my technique."