CHICAGO -- If Mark Buehrle had his way, he'd probably have umpire Eric Cooper calling balls and strikes every time he takes the mound.

Cooper was calling the shots behind the plate at U.S. Cellular Field for Buehrle's perfect game on Thursday against the Rays. In a strange coincidence, Cooper was the home-plate umpire when Buehrle tossed his first no-hitter back on April 18, 2007, against the Rangers, also at The Cell.

"After the game, we certainly talked about this being the second one with Buehrle," Cooper said. "I thought about it more then than when I was actually working.

"I'm certainly aware of the situation, especially late in the game, just because of the way the fans are reacting. But it doesn't differentiate how I call the game. I have the same approach whether the score is 0-0 or 10-0, or whether there is a perfect game or no-hitter going. I try to call strikes, strikes and balls, balls."

Cooper has worked three no-hitters in his umpiring career, both of Buehrle's and also Hideo Nomo's no-no on April 4, 2001.

Both of Buehrle's no-hitters occurred at home, so the fan distractions can be quite intense. But part of the job of an umpire is to block out the background noise and focus on the task at hand, Cooper said.

"Certainly, late in the game, when the fans are on their feet and they're loud, they want every pitch to be a strike, and not every pitch is a strike," Cooper said. "That's the time when you really need to kind of take a deep breath and really focus on what's going on and not get caught up in the moment."