KANSAS CITY, Mo. (AP) — 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. I wasn't making my pitches. I wasn't in the strike zone. When I did get it in the strike zone, they hit it."

Joe Smith (1-0) got the victory with 1 1-3 innings of hitless relief.

Expected by most observers to remain also-rans in the AL Central this year, the Indians and Royals had not been first and second this late in the season in any order since May 31, 1999, when Cleveland led the Royals and White Sox by 10 games en route to a fifth straight division title. That also was the last time the Indians started a season as well they've started this one, winning 12 of their first 16.

One out after Duncan's double, Michael Brantley walked. Matt LaPorta grounded into a fielder's choice and pinch-runner Adam Everett scored on shortstop Alcides Escobar's throwing error. Jack Hannahan followed with an RBI double and Sizemore made it 7-3 with his third hit.

"We didn't help ourselves, that's for sure," Royals manager Ned Yost said. "We really struggled to command the ball, especially out of the 'pen. Leadoff walks and the 10th inning hurt us."

The Royals scored twice to take a 3-2 lead in the sixth on Melky Cabrera's RBI double and an RBI single by Alex Gordon, who tied his career high with a 12-game hitting streak, the longest in the majors this year.

Billy Butler's single made it four straight hits off starter Carlos Carrasco and put runners at first and second. But the right-hander escaped further damage by retiring Kila Ka'aihue on a foul pop and coaxing a double-play grounder out of Jeff Francoeur.

Royals starter Kyle Davies was charged with two runs and seven hits in six innings. He struck out seven, walked none and was relieved by Jeremy Jeffress, who walked Brantley on four pitches to start the seventh and then threw wildly to first on a pickoff attempt, allowing the runner to move up two bases.

LaPorta, after hitting an RBI single that tied it 3-all, went to second on Jeffress' wild pitch. With one out, Jeffress walked Sizemore and Asdrubal Cabrera and handed a bases-loaded jam to reliever Aaron Crow, who struck out Shin-Soo Choo and retired Santana on a pop fly.

"On a positive note, Kyle Davies pitched great — six strong innings," Yost said. "Aaron Crow did a phenomenal job with the bases loaded."

Santana had an RBI double in the first and Cleveland took a 2-1 lead in the third on Choo's sacrifice fly.

Wilson Betemit had a sacrifice fly in the second for the Royals and singled leading off the seventh, tying his career best with a 10-game hitting streak.

NOTES — It was Butler's 25th birthday. ... The two AL Central leaders will play each other seven times in 11 days, including a three-game series next week in Cleveland. ... Carrasco's first major league win was against the Royals last Sept. 17. He pitched 6 1-3 innings and gave up three runs on seven hits. ... Gordon also had a 12-game hitting streak in 2008. ... The Royals failed to score in the eighth despite two Cleveland errors.