Muhammad Ali and a sell-out crowd watched as the Yankees beat Boston for the first time in nine games this season, with Jorge Posada and Melky Cabrera hitting three-run homers in New York’s 13-6 victory last night.

Posada had three hits and three RBIs. Johnny Damon and Mark Teixeira also connected for New York.

Damon’s third-inning shot was his third in three days, Cabrera and Posada went deep in the fourth, when the Yankees scored eight runs. Teixeira delivered the final blow with his 28th homer leading off the seventh.

Despite a career-high seven walks, Joba Chamberlain (8-2) lasted five innings to win his fourth consecutive start.

Casey Kotchman hit a two-run homer for Boston and Dustin Pedroia also went deep. David Ortiz went 0-for-5 and was booed lustily in his first game at Yankee Stadium since he said the union confirmed his name was on the list of 104 major leaguers who tested positive for performance-enhancing drugs in 2003.

The AL East-leading Yankees increased their lead over Boston to 3 1/2 games with their fourth consecutive win. Red Sox ace Josh Beckett is scheduled to face A.J. Burnett on Friday.

Boston played without All-Star outfielder Jason Bay and shortstop Jed Lowrie departed in the fourth inning with an irritated left forearm.

Chamberlain gave up four runs and six hits. He hasn’t lost since June 18 against Washington.

The only testy moment came in the eighth when Mark Melancon threw a pitch over the head of Pedroia, then hit the Boston leadoff man.

Posada walked with Pedroia down the first-base line and Francona came out to talk with plate umpire Derryl Cousins. Francona said Cousins issued a warning against further trouble.

I’m pretty sure Beckett will retaliate tonight, probably by hitting Jeets, Tex, or A-Rod.

The Yankees need to win at least one more game this weekend to ensure they finish the series ahead of the Sox. Of course a sweep would be sweeter!