BOSTON -- Theoretically, technically, mathematically, of course there is no such thing as a "must-win game" for a team leading its division by 4 1/2 games in mid-September.

But Saturday at Fenway Park, it felt like the necessity of victory was present for the Boston Red Sox. They didn't need this victory as badly as, oh, perhaps the Union needed the big "W" at Gettysburg. But this one was needed on any level you care to examine.

The Red Sox had lost five straight games to the New York Yankees dating back to June. The Yankees were clearly in a resurgent mode, the kind of thing that stirs collective, deeply unpleasant memories in New England. And the type of loss the Red Sox had suffered most recently, the evaporation of a late five-run lead in a matter of minutes on Friday night, had the potential to be emotionally debilitating.

The Red Sox needed a victory over the Yankees, not only for their well-being in the American League East standings, but for their basic, human peace of mind. If they were going to be successful in ending the Yankees' nine-year reign in the division, they needed to beat them head-on, better Sunday night than never, but better Saturday than Sunday night.

The way it worked out, as disappointing as Friday night had been, Saturday was that uplifting for the Red Sox. Their 10-1 victory over the Yankees showcased every part of their game, proved once again that the quality of resilience is still with them and gave them some breathing space for the stretch run and in the standings.

"We needed a nice bounce-back day," Red Sox manager Terry Francona said. "I thought we were very spirited, had good energy and played a very good game."

It was not as easy as the final score indicated, but that was part of the charm. This was a one-run game until the sixth inning, and it didn't get out of hand until the seventh, when Boston caught up with the lesser half of the New York bullpen.

Credit Red Sox starter Josh Beckett with halting the Bronx Bombers' momentum and containing their offense. And give him another point in his AL Cy Young Award candidacy. Beckett and Yankees starter Chien-Ming Wang came to this game with identical 18-6 records, and this was being billed in some quarters as a battle for The Cy. This game wasn't about that, and the hype tended to ignore the work of C.C. Sabathia, Justin Verlander, Kelvim Escobar and other worthies. But all right, Beckett left Fenway Park looking more like an award-winner than Wang did.

What was particularly praiseworthy about Beckett's performance was that it followed one of those here-we-go-again first innings. Beckett gave up only one run, on a Derek Jeter home run, but he had to throw 30 pitches to get out of the first.

How many times have you seen the Yankees drive pitch counts into the stratosphere from the first batter on? They work counts, they're patient, they're selective, they're disciplined and they probably lead the galaxy in decent pitches fouled off. It can be a long, laborious and painful process for the opposing pitcher, but Beckett hung on and hung in. His seven innings showed only that first-inning run allowed, three hits, two walks and seven strikeouts.

Yankees Coverage
Jeter's late homer lifts Yanks
Yanks gear up for lesser opponents
Chamberlain springs curve on Sox
Notes: Peace of mind for Posada

Red Sox Coverage
Schilling's gem ends with loss
Bauman: Game mirrors Classic duel
Sox don't take lead for granted
Notes: Matsuzaka pushed back
Season Series
Yankees win 10-8
• 9/16: Yankees 4, Red Sox 3
• 9/15: Red Sox 10,Yankees 1
• 9/14: Yankees 8, Red Sox 7
Previous season series
2006: Yankees 11, Red Sox 8
2005: Yankees 10, Red Sox 9
2004: Red Sox 11, Yankees 8

Francona said that Beckett "pitched like the ace of a staff today. Against the best lineup in baseball, he went out there and did exactly what we needed."

Beckett was the definition of an ace in this game. He later turned aside a question about relishing this role, saying that he wanted only to execute his pitches, but this was a situation that required action rather than verbiage. Beckett was exactly what the Red Sox needed, with or without relishing.

The Red Sox broke this game open with a blended festival of hits and walks. Young Jacoby Ellsbury continued to be a revelation, with two more hits and three more RBIs. He has hit safely in each of his 13 games since being recalled from the Minor Leagues on Sept. 1 and has a .426 average over that period. He entered the game in the fifth inning as a pinch-runner and stayed in the game, playing left field.

Therein was the one troubling development for the Red Sox. Ellsbury came in when Kevin Youkilis was hit on the right wrist by a pitch from Wang. X-rays on the wrist were negative, but Francona described Youkilis as "very sore."

"He's intact," Francona added, "but he's very sore."

This follows the episode in the last Yankees-Red Sox series, in which Joba Chamberlain was ejected for throwing two pitches in the vicinity of Youkilis' head. But nobody was claiming an anti-Youkilis vendetta on the part of the Yankees. Still, the Red Sox simply can't afford the loss of another important member of the lineup. Youkilis apparently has a better chance of remaining healthy when the Red Sox are playing against one of the other 28 clubs.

Beckett dismissed any discussion of retributions and warnings in regard to hitting Jason Giambi with a pitch in the seventh. The two teams were too busy trying to "grind it out," Beckett said, to engage in a feud.

"That's why our games usually last between 12 and 13 hours a day," Beckett said.

It only seems that way. After the four-hour, 43-minute marathon on Friday night, Saturday's game was three hours and 37 minutes. That's a long game in the other league, but it's practically a sprint for these two clubs.

But for the Red Sox, this one would have been more than worth it if it took all weekend. They needed a victory over the Yankees for many varied and valid reasons. The fact that the victory came in a 10-1 package was a bonus.

They will leave this series no worse than 4 1/2 games ahead with 12 games to play. There will be no sweep and no lasting notion of Yankees invulnerability down the stretch. This was one Red Sox had to have, and they fully earned it.