Struggling with his command, Pettitte faced eight Boston hitters in the pivotal fifth inning and could only retire two, allowing a run-scoring hit to David Ortiz, issuing a bases-loaded walk to Mike Lowell and throwing a wild pitch that brought home the go-ahead run.
"It makes you sick to your stomach," Pettitte said. "I'm probably not going to sleep well tonight, that's for sure."
The Yankees have lost seven consecutive games for the first time since 2000. Even at this early point, Boston is beginning to pull away in the American League East, having extending its lead to 6 1/2 games over last-place New York.
The calendar says it's early. But the Yankees seem to be thinking late.
"Every game is a must-win for us now, even though it's April," said Johnny Damon. "We have to win -- we're not going to be able to catch up if we don't."
Derek Jeter continues to insist that it's too early to push the Yankees' panic button. But that doesn't make the struggling any more palatable.
"This is the time when you find out how good a team this is," Jeter said.
The Yankees looked to be in good shape early, putting Daisuke Matsuzaka on the ropes with a four-run fourth inning, sending nine batters to the plate and delivering a lead to Pettitte, by far the most effective New York hurler through the season's early battles.
As Jason Varitek tossed his bat aside with a free pass -- the season-high fifth issued by Pettitte -- midnight again struck too early for a Yankees starter and manager Joe Torre was making that long, jacketed walk to the mound, again calling on the right arm of reliever Scott Proctor.
It was just last season that Proctor led the league with 83 relief appearances, some of which played out with Proctor ignoring a clicking sound from his pitching arm, but already the Yankees' inability to get deep into games has put Proctor back on pace to eclipse that statistic.
Both Proctor and Luis Vizcaino, who pitched an ineffective eighth inning, have appeared in 14 of the Yankees' first 21 games, and as long as starters continue to shy away from the sixth and seventh innings, it is a trend with no end in sight.
"We're proud of our bullpen," Torre said, "but the most important thing is not having to overuse it. We've overused it. I don't anticipate it's going to continue to be that way. We feel the starters are going to start taking the ball and running with it."
Whenever that beginning comes, it wasn't on Friday. Pettitte, who also allowed a two-run homer to Kevin Youkilis in the third inning, was unable to make it into the fifth for just the second start this year. But that's nothing new at Yankee Stadium, where just one Yankees starter has pitched six innings: Kei Igawa, who spent Friday night in the bullpen.
Pettitte allowed five runs, six hits and recorded five strikeouts in 4 2/3 innings. He gauged the Yankees' clubhouse to be one of New York's least desirable destinations on Friday evening.
"I think everyone's down and extremely upset," Pettitte said. "How can you not be? We haven't won a game in a week."
"He's our big horse," said Jason Giambi, who went 2-for-3 in the loss. "We have a lot of respect for him. We hope he doesn't get down on himself, because we really need him."
Throughout this cold stretch, with the exception of a sterling shutout performance by Toronto's A.J. Burnett on Thursday, putting up crooked numbers has not been the biggest issue for the Yankees. The challenge has been keeping digits off the matrix boards, and Friday marked the eighth consecutive game in which Yankees pitchers allowed six or more runs.
"We just can't sustain anything," Torre said. "I think offensively we're used to scoring runs. We just haven't been able to make them stand up."
New York became the first Major League club to bat around against Matsuzaka, sending nine batters to the plate in a 41-pitch frame and scoring four runs via three hits and an error, including Damon's check-swing two-run single to right and RBI hits by Jorge Posada and Jeter.
Matsuzaka walked four and struck out seven in a 117-pitch, five-hit effort, yielding to the bullpen after six innings.
Julio Lugo chipped in with insurance runs in the sixth and eighth innings, homering off Proctor and driving an RBI double facing Vizcaino before the Red Sox put up the fireworks that most troubled the Yankees.
Boston chased away any thoughts of a New York rally with a four-run outburst in the ninth inning against Mariano Rivera, the club's lone underworked reliever, who volunteered for the extra assignment and was rewarded by watching his ERA swell to 12.15.
"You aren't going to fix it sitting down," said Rivera, who was also roughed up for two runs and three hits in his other appearance against the Red Sox this season. "You're going to fix it going out and playing hard, making things happen."
The Red Sox have now won six straight games against the Yankees, including the final two contests to end the 2006 season. Meanwhile, the Yankees haven't lost seven straight games in April since 1989, a historical footnote that nobody around the Bronx is especially pleased to dredge up.
"We're much better than this," Torre said. "We have the ability and the capability. We just have to play better ballgames."