But the difference is that the first player saw that he was about to be hit and tensed his neck, which limited the sharp back-and-forth jolt of the head that sends the brain crashing against the sides of the skull.

NEWYORKER: Offensive Play

There would, however, be an immediate shift in momentum as Berdych tensed up in game two of the second set and allowed Federer to break to 15 with a fine crosscourt forehand pass.

BBC: Wimbledon 2010: Roger Federer stunned by Tomas Berdych

"We knew we hadn't played very well for 40 minutes, and we just tried to generate some energy because we were all tensed up, " Carlyle said.

WSJ: Reimer SO sends Devils to 10th straight loss