Chicago ? The Kansas City Royals wanted Bruce Chen to show more aggression. He finally did.

Chen outpitched Jake Peavy for his first win in six weeks, Billy Butler hit his career-high 22nd homer, and the Royals beat the Chicago White Sox, 5-2, on Tuesday night.

The White Sox had won 10 of 13, but saw their lead over Detroit in the AL Central shrink to a half game when the Tigers beat the New York Yankees, 6-5, earlier in the night.

Gordon Beckham hit his first career leadoff homer for Chicago, and the White Sox scored again in the sixth after Kansas City tied it in the top half. But RBI singles by Tony Abreu and Alex Gordon off Peavy (9-8) in the seventh gave Kansas City a 3-2 lead.

Butler added to it in the eighth with a two-run drive off Nate Jones after Mike Moustakas walked, and the Royals hung on from there, giving Chen (8-9) his first win since June 26.

The left-hander gave up two runs and seven hits in 6 2/3 innings and finally came out on top after going 0-3 in his previous seven starts. It was a big improvement over his previous outing, when he got knocked out in the third against Cleveland after being staked to a six-run lead.

He and manager Ned Yost had a long talk about being aggressive following that game, which the Royals eventually won. The message? Go after the hitters, establish the fastball.

“His last three or four starts, he comes out and he hasn’t established his fastball,” Yost said. “All he’s doing is throwing 82, 83, trying to get his control down, but he’s got nothing to speed the bats up so they sit soft.”

Now, the Royals are 4-3 in August after dropping 19 of 26 in July.