NEW YORK— At this rate, the relentless Boston Red Sox might eliminate the New York Yankees sooner than anyone thought.

Jason Bay drove in four runs, Dustin Pedroia hit a grand slam and Boston routed the listless Yankees 11-3 tonight, putting an emphatic dent in New York's dwindling playoff chances.

"I never write the Yankees off until the season's over and the standings are set," Pedroia said. "They've been around too long and been in the playoffs for such a long time that we're definitely not counting them out."

Paul Byrd beat the Yankees in a crucial game for the second consecutive year, and David Ortiz reached base four times for the second straight night.

In their final regular-season trip to Yankee Stadium, the Red Sox have outscored their longtime rivals 18-6 in the first two games of this three-game series.

"We just dug ourselves a bigger hole," New York's Johnny Damon said. "This is definitely a tough time for us."

Pedroia's first career slam capped a seven-run eighth inning and sent hordes of booing Yankees fans shuffling toward the exits. With co-chairman Hank Steinbrenner in attendance, New York dropped seven games behind Boston, which leads the AL wild-card race by 2 1/2 games over Minnesota.

The Yankees haven't missed a postseason since 1993.

"It couldn't have been any worse the first two games, but we've got to come back tomorrow," New York shortstop Derek Jeter said. "What we've done before makes no difference."

In a game they needed badly, the injury-depleted Yankees gave the ball to Sidney Ponson (7-5). He lasted 4 2-3 innings and dropped to 3-13 with a 6.95 ERA in 22 starts against the Red Sox.

Boston tries for a sweep Thursday with lefty Jon Lester on the mound against 16-game winner Mike Mussina. The Red Sox are 3 1/2 games behind first-place Tampa Bay in the AL East.

Byrd (9-11) has won six of his last seven starts following a five-game losing streak. He stymied New York's struggling hitters with floaters and soft stuff, just as he did last October when the right-hander won at Yankee Stadium to clinch a first-round playoff series for Cleveland.

"When I walked into this clubhouse, I remembered getting champagne poured on me right over there, about 20 feet away, and I got a smile on my face because it just has a good memory to me," Byrd said. "And I know this is the last year of the stadium, so you think about that."

Still using his old-fashioned windup, Byrd allowed two runs and five hits in six innings. He struck out five and improved to 2-1 in three starts since Boston acquired him from the Indians this month.

Also a Red Sox newcomer, Bay hit a two-run double in the first and an RBI triple in the eighth when Boston battered relievers Jose Veras and David Robertson.

Bay has six RBIs in his first two games against the Yankees.

"Two games doesn't make a lifetime. It doesn't make a career," he said. "The whole month I've been here has kind of been a Red Sox-Yankee series for me."

Bay is hitting .347 with four homers and 24 RBIs in 23 games since Boston acquired him from Pittsburgh in a three-team trade July 31 that sent Manny Ramirez to the Dodgers.

"I'm not writing a Hall of Fame career just yet. But it's been nice to get off to the start I've gotten off to. It takes a little bit of pressure off," Bay said.

The gritty Pedroia, last season's AL Rookie of the Year, hit a shot off Robertson that landed on the netting above New York's retired numbers in left-center.

In the Boston bullpen, Jonathan Papelbon spread his arms with delight as he watched Pedroia circle the bases.

"He's a beauty. He's kind of, I think, the Energizer Bunny for this team," Bay said. "You know, he's the one that stirs stuff up. Every team has got to have that guy."

Manny Delcarmen fanned two in a perfect seventh to preserve a 4-2 lead.

Boston broke a 2-all tie in the fifth after Pedroia's perfect hit-and-run single put runners at the corners. Consecutive walks to Ortiz and Kevin Youkilis forced in the go-ahead run before Bay's sacrifice fly made it 4-2 and chased Ponson, 0-3 in his past four starts.

"I just didn't do my job," Ponson said. "The season's getting shorter. We don't have many games left."

Jason Giambi homered for the Yankees in the ninth.

"We really have to come out and be perfect tomorrow," Damon said.