NEW YORK(AP) The Boston Red Sox are 5-0 against the New York Yankees for the first time in 24 years, doing a lot better at the new Yankee Stadium than the home team.

Jason Bay hit a three-run homer in a four-run first inning against Joba Chamberlain , and the Red Sox beat New York 7-3 on Tuesday night for a rainy two-game sweep in the first trip to their rival's $1.5 billion ballpark.

''I think Jason Bay is the only guy that thought it was a nice night out there,'' Red Sox manager Terry Francona said.

Weather was suited more for winter sports than baseball for the second straight night, with a cold rain falling throughout the late innings that made the mound slippery.

''I'd much rather take this,'' said Bay, who was born in Trail, British Columbia, ''than 95 and humidity, as weird as that may sound. This is a nice spring/summer day sometimes where I'm from, so, you know, I enjoy this.''

Bay, 10 for 18 (.556) with three homers and 10 RBIs against the Yankees this season, homered into the left-field seats. Johnny Damon hit a three-run homer to right in the third for New York. There have been 38 homers at Yankee Stadium, two shy of the record for the first 11 games at a big league park, set at Houston's Enron Field in 2000.

Boston has outscored the Yankees 38-23. In 1923, the Red Sox lost their first five games at the original Yankee Stadium.

''They outplayed us. They outpitched us. At this point in the season, they are a better team than us,'' Damon said.

Despite an announced crowd of 46,810, many of the most expensive seats again were empty. Just 54 of the 98 first-row Legends Suite seats costing $2,500 were occupied in the first inning, and three of the first nine rows behind the plate were mostly vacant. Later, New York City Mayor Michael Bloomberg, wearing a Yankees jacket, sat just to the third-base side of the plate in one of those front-row seats.

Rain began falling when Jose Veras relieved Chamberlain in the sixth, and many of the fans in the Legends Suite cleared out into the three exclusive restaurants and lounges.

''I know that there wasn't a lot of fans in those sections right behind the dugout,'' AL MVP Dustin Pedroia said. ''I don't know why.''

New York dropped to 6-5 overall at its new home following three straight losses and is 13-13 overall.

'It's not any fun, that's for sure. It's frustrating,'' Yankees manager Joe Girardi said. ''It's not the way you want to start the season, but it's where we are. We've got to do something about it.''

Josh Beckett (3-2) bounced back from two poor outings and allowed 10 hits in six-plus innings, lowering his ERA from 7.22 to 6.75. Hideki Okajima followed with six straight outs.

''Some laboring times, but I made pitches when I had to,'' Beckett said.

Chamberlain (1-1) allowed hits to his first five batters, then recovered to strike out a career-high 12 in 5 2-3 innings, including nine looking. But it was too late.

Pitching a day after his mother was arrested in Nebraska on suspicion of selling methamphetamine to an undercover police officer in February, Chamberlain allowed four runs and six hits, becoming the fifth pitcher since 1900 to strike out 12 in 5 2-3 innings or less. The previous was Philadelphia's Cole Hamels in 5 1-3 innings against Atlanta on July 24, 2006, according to the Elias Sports Bureau.

''It was a terrible start,'' Chamberlain said. ''I definitely let my team down, giving up four in the first.''

Notes: Before the game, the Yankees put All-Star catcher Jorge Posada on the DL with a strained right hamstring. Boston was without 1B Kevin Youkilis (tight left side) and lost CF Jacoby Ellsbury to a tight right hamstring in the fourth inning. ... In a rehab start for Triple-A Pawtucket, Red Sox RHP Daisuke Matsuzaka allowed two hits in 2 2-3 scoreless innings. He has been on the 15-day DL since April 15 because of a mild right shoulder strain. ... Chamberlain became the first Yankees pitcher to strike out 12 since Mike Mussina against Seattle on May 7, 2003.