Kansas City, Mo. ? Round one in the showdown between unlikely AL Central leaders went to Cleveland.

Pinch-hitter Shelley Duncan’s RBI double sparked a four-run 10th inning, and the Indians beat Kansas City, 7-3, on Monday night to widen their division lead to two games over the equally surprising Royals.

Duncan batted for Travis Buck after Carlos Santana drew a walk from rookie left-hander Tim Collins (1-1) to start the 10th. Duncan hooked an RBI double into the left-field corner, driving home the tiebreaking run in Cleveland’s fourth straight win.

“He hits lefties,” Indians manager Manny Acta said. “He’s our best option against lefties. He’s proven that over the years.”

In perhaps the most encouraging sign for the Indians, Grady Sizemore, in his second game back from knee surgery, added an RBI single and was 3-for-5 after going 2-for-4 on Sunday in his first game since May 16, 2010.

“The reason I came over here was to enjoy this guy from the dugout after seeing him over the last seven-eight years,” Acta said. “It’s nice to have him back.”

Collins, one of three rookie relievers who have played a big part in Kansas City’s strong start, gave up four hits and four runs in one inning.

“Real bad,” he said. “It’s always a rough night when you go out and give up four runs.”