CLEVELAND (AP) -An 18-2 record pitching for any team is impressive.

Cliff Lee 's season has been truly remarkable because he's been practically unbeatable for team that's been less than mediocre.

The Indians' left-hander recorded his AL-best 18th victory and won his seventh straight decision as Cleveland beat the Kansas City Royals 10-3 on Thursday.

Lee, the Cy Young award front-runner, allowed three runs - two earned - and six hits in seven innings. He struck out seven and induced four double plays. Lee leads the AL in wins, winning percentage (.900) and ERA (2.43) for a team that's 59-67 and, until recently, was fighting to get out of last place in the Central Division.

''He's had a great year,'' said Indians center fielder Grady Sizemore , who didn't have a bad day himself with a career-high seven RBIs. ''It's not a surprise anymore when he goes out there and pitches like that.''

''It's remarkable what he's done,'' Indians manager Eric Wedge said.

Lee hasn't been basking in his success.

''I'm focused on my next start,'' he said. ''It's against Detroit (next Tuesday). That's where my focus is.''

While the Indians completed a 7-3 homestand, the Royals have lost five straight, 12 of 14 and head back to Kansas City after a 1-8 road trip.

''It wasn't a good day or road trip,'' manager Trey Hillman said after his team made two errors, leading to four unearned runs. ''It's frustrating, obviously.''

Sizemore, who was 4-for-5, had a three-run triple in the second, a run-scoring single in the sixth and a three-run homer in the eighth.

Shin-Soo Choo hit a two-run homer in the third and Jhonny Peralta hit a solo home run in the seventh for Cleveland, which swept the three-game series.

Zack Greinke (9-9) allowed five runs in five innings. Despite the errors by his defense, the right-hander took the blame for the loss.

''I usually do a good job of getting out of those problems,'' he said. ''It's not like those errors would have ended the inning. I'm not making good pitches after that.''

Lee didn't give his latest outing a favorable review.

''I didn't feel like I had my best stuff,'' he said. ''I had to battle. The double plays were big. Give credit to the offense. When you get five runs in the first three innings, it gives you some cushion.''

Lee walked two batters in the second, but was assisted by the first double play. He retired eight in a row at one point before pinch-hitter Jason Smith reached on a one-out error by third baseman Jamey Carroll in the fifth.

John Buck , in a 3-for-45 slump, followed with a line drive single to left for Kansas City's first hit and Mark Teahen doubled in both runners. Tony Pena Jr. singled, scoring Teahen and making it 5-3.

Mike Aviles followed with another single before Lee got Esteban German to hit a ground ball to Carroll, who stepped on third and threw to first for a double play.

Lee also had double plays turned behind him in the sixth and seventh.

''You're going to get yourself in tough situations and you have to limit the damage,'' Wedge said. ''Cliff has done a good job of that this season.''

Lee is unbeaten at Progressive Field in 2008, going 8-0 with a 2.39 ERA in 11 starts.

A fielding error by Pena at short and singles by Carroll and Asdrubal Cabrera loaded the bases in the second. Sizemore tripled to left-center for a 3-0 lead.

A throwing error by first baseman Billy Butler started Cleveland's rally in the third. Choo homered to center with one out. Peralta's homer led off the seventh.

Sizemore's three-run homer came off left-hander Josh Newman . He entered Thursday in a 12-for-65 slump (.185) over his last 17 games.

''Every day is different,'' he said. ''I feel good and I'm seeing the ball well.''

Greinke is 2-5 in his last 10 starts and has failed three straight times to get his 10th win.

Notes: Hillman is undecided about who will start Saturday and Sunday against Detroit. ... Royals 3B Alex Gordon , who missed Monday's game because of a stiff back, was pulled for a pinch-hitter in the fifth with upper right quad tightness. ... OF Mitch Maier , who broke three bones in his face after being hit by a pitch Wednesday, was placed on the 15-day disabled list. OF Joey Gathright was recalled from a rehab assignment at Triple-A Omaha. ... The Indians turned a season-high five double plays. ... The Indians are 12-5 in August. ... The Indians held a moment of silence before the game for Congresswoman Stephanie Tubbs Jones, who died Wednesday. Tubbs Jones represented Ohio's 11th District, which includes areas of Cleveland.