NEW YORK — Joba Chamberlain pitched as if his place in the New York Yankees' postseason rotation was at stake.

Winless in eight starts since beating Boston on Aug. 6, Chamberlain responded with his first victory in 1 1/2 months and led the Yankees over the Red Sox, 9-5, last night.

Earlier this week in Anaheim, Calif., manager Joe Girardi and Yankees coaches met with the 23-year-old right-hander.

"I wouldn't say that we read him the riot act. We just had a discussion that we knew he was capable of pitching better and that we need to see him pitch better," Girardi said.

Chamberlain (9-6), slated to be the Yankees' No. 4 starter in the AL Championship Series and World Series, had scuffled while the Yankees held down his pitch count and innings to keep him under his preset and undisclosed limits. He had gone 0-4 with an 8.42 ERA in eight starts since beating Boston.

Yesterday, he retired his first 11 batters before Victor Martinez's solo homer and allowed three runs and five hits in six innings, throwing 86 pitches. He struck out five and walked one.

"You've just got to be challenged," Chamberlain said. "There's a lot of people in this game that want your job and you know when it comes down to it you have to look like they're going to try to take money off your table and try to take away wins and a championship away from you."

Alex Rodriguez homered, drove in four runs and tied a career high with three steals as the Yankees, already assured of a playoff berth, lowered to three the magic number for their first AL East title since 2006.

Rodriguez's two-run homer in the third was New York's team-record 127th at new Yankee Stadium. New York hit 126 homers at old Yankee Stadium in both 2004 and 2005, according to STATS LLC.

Jon Lester (14-8), Boston's best starter during the second half of the season, crumpled to the mound in pain when struck near his right knee by Melky Cabrera's liner in the third inning. His head back and eyes closed, Lester was looked over by trainers from both teams. After about 2 minutes, Lester hobbled off with the assistance of Red Sox trainer Paul Lessard, and David Ortiz helped him down the dugout steps.

"When it first happened, it looked terrible. It sounded terrible," Red Sox manager Terry Francona said.

X-rays were negative, and Boston said Lester had a bruised quadriceps.

"It hit off my knee going about mach seven," Lester said. "It hit me in a good spot, where it didn't do too much damage that, hopefully, I won't miss any time."

He allowed five runs and eight hits in 2 1/3 innings.

"I had good stuff tonight. It was one of those nights they made it seem like I didn't," Lester said.

New York has won seven of eight against Boston, including a four-game sweep at Yankee Stadium last month after starting the season 0-8 against the Red Sox.

The Yankees, who led 5-0 after three innings, also swiped seven bases in seven tries off Jason Varitek, their most steals since they had eight at Oakland on June 2, 1996.

WHITE SOX 2, TIGERS 0

Jake Peavy (2-0) allowed six hits over seven innings and Gordon Beckham broke up Eddie Bonine's no-hit bid with a two-out, two-run homer in the bottom of the sixth inning as Chicago slowed Detroit's pursuit of the AL Central title.

TWINS 9, ROYALS 4

Michael Cuddyer hit his 30th home run and walked with the bases loaded and visiting Minnesota moved within two games of first-place Detroit in the AL Central with a victory over Kansas City.

ATHLETICS 3, ANGELS 0

Rookie Gio Gonzalez (6-6) allowed four hits over 6 1/3 innings to outpitch Jered Weaver (15-8), and Adam Kennedy and Daric Barton hit run-scoring singles to lead visiting Oakland. Los Angeles' magic number for clinching its fifth AL West title in six years remained at four.

INDIANS 4, ORIOLES 2

Fausto Carmona (4-12) gave up two runs and nine hits over six innings to win for the first time since Aug. 23, and Luis Valbuena homered, helping host Cleveland beat Baltimore to end its 11-game losing streak.

BLUE JAYS 5, MARINERS 0

Roy Halladay (16-10) struck out nine in a seven-hitter for his third shutout of the season, Aaron Hill hit a two-run homer and Jose Bautista also drove in two runs, leading host Toronto past Seattle.

RANGERS 8, RAYS 3

Ian Kinsler homered to become a 30-30 (home runs/stolen bases) player for the first time, Julio Borbon had three hits and host Texas clung to its slim playoff hopes by beating Tampa Bay.