CHICAGO -- Now this is the Mark Buehrle that the Royals have learned to loathe.

Buehrle recaptured his old hold over the Royals with seven shutout innings on Friday night as the hot Chicago White Sox cooled off the Royals, 8-2, at U.S. Cellular Field. He got plenty of help from another frequent Kansas City annoyance, catcher A.J. Pierzynski, who banged two homers for four RBIs.

The white-hot Sox, just a half-game behind Detroit in the American League Central, have won six straight and 19 of their last 23 games. The Royals, their three-game spurt snagged, still have won 10 of their last 14.

In his two earlier starts against the Royals this year, Buehrle was 0-2 with a 5.84 ERA. Not at all like the guy who had beaten them 20 times in his distinguished career. But now make that record 21-11 with a nice 3.56 ERA.

"It was vintage Buehrle," said the Royals' Scott Podsednik. "He didn't walk anybody and stayed away from the big inning. We got a couple of hits here and there but we just couldn't get anything going against him. He was sharp."

Buehrle did walk two in fact and gave up six hits but the Royals couldn't crank up their Major League-leading bats at the right times. Only Yuniesky Betancourt's two-run homer in the ninth inning kept them from a shutout. And that came against Jeff Marquez, a right-hander who was making his Major League debut.

With this victory, Buehrle is 5-1 in his last six starts.

"He was tough tonight," Royals manager Ned Yost said. "He would bend but we couldn't break him."

White Sox manager Ozzie Guillen has seen his starting pitchers go 18-5 with a 2.27 ERA in the last 29 games.

"I'm not surprised. When you see Buehrle throw almost 40 pitches in the first few innings and then turn the thing around right away and be what we know he is going to be, I know a lot of balls are going to be in play," Guillen said.

With 25,137 noisy fans on hand, Buehrle did get up to 114 pitches and when he walked David DeJesus to start the eighth inning, Guillen went to his bullpen.

"We try to get his pitch count up and we were successful at that a little bit in the early innings but he got settled down and started banging more strikes," Yost said. "He kept the ball down real well and was getting the low strike called for him which helped him a lot. And we just couldn't do anything with him."

Royals starter Bruce Chen was given a quick hook, right after Pierzynski's solo homer gave the White Sox a 3-0 lead in the fourth inning. That was a medical concern behind that.

"Bruce didn't have it tonight," Yost said. "After his last start, Bruce got strep throat and was battling that. He felt better yesterday, but when he went back out, there was not much life left on his fastball. We were just going to go with him as long as we could after he gave up the two runs. When the home run made it three, we decided that was enough."

Chen admittedly made a fielding blunder in the second after Paul Konerko and Carlos Quentin opened the inning with singles. Pierzynski bunted and, although catcher Jason Kendall saw a possible force-out at third base, Chen threw to first for the out.

"Kendall was screaming 'third' but Bruce didn't hear him," Yost said.

Andruw Jones made the most of the mistake by banging a two-run single deep to left field.

"I don't know what I was thinking," Chen said. "It caught me off guard. I broke to the line when I saw him get down the bunt. It was kind of hard so I thought, 'Oh, man, I better hurry up and get to it.' And I wasn't even thinking about going to third. I should've known that Konerko was at second and would've been an easy out."

The White Sox went ahead, 4-0, against reliever Kanekoa Texeira and broke it open in the eighth with four runs against Victor Marte. Pierzynski's three-run, 409-foot blast to right field capped it off.

Pierzynski's two homers boosted his career average against the Royals to .303 with 11 homers, 59 RBIs.

Chen, it was learned, had developed a case of strep throat after his previous start at Anaheim in which he pitched a perfect game for six innings and won 4-2.

He insisted he felt well enough to pitch against the White Sox.

"We're trying to win ballgames here and I don't think it's fair for my teammates to go out there and not feel 100 percent," he said. "I felt fine and I felt like I could pitch and I just got beat today. I can't blame it on strep throat."

When Betancourt banged his sixth homer in the ninth, it ended a string of 18 1/3 consecutive scoreless innings by White Sox pitchers.

But not much else has gone wrong lately for the White Sox.

The Royals had to cope with just their second loss in seven games so far on this road trip.

"We kind of take it in stride," Yost said. "You know you're going to lose games but you try to stay as level-headed as you can about it. You don't get too crazy when you win games, you don't get too crazy when you lose games."