Mike Celizic

Manny Ramirez is down with a back injury, and by his estimate, it will be a week before he’s back. Given the uncertain nature of back injuries, it could be longer. What it means is that Boston is about to find out just how good its vaunted pitching staff is.

The Red Sox have been averaging more than five runs a game, but that’s not going to continue without Ramirez, one of the best hitters in baseball and the team’s clean-up hitter. He’s the guy who protects David Ortiz, the team’s top run-producer, and, while Mike Lowell can move up into his slot, Ramirez’s absence substantially weakens the bottom of the order. You don’t lose him and not feel it.

But hitting is not why Boston still have one of the biggest divisional leads in baseball. They are where they are because their team ERA is the best in the American League and the second best in all of baseball. And they’ll stay where they are if their pitchers can stand up to the challenge.

They got a huge boost when it became apparent rookie Clay Buchholz could provide a start whenever needed. Saturday, just hours after being called up by the Red Sox, Buchholz no-hit the Baltimore Orioles. It was his second career start.

Still, the pressure on Boston is growing by the day. They didn’t just all but put New York in the playoffs this week, they also made the Yankees believe that if they get to October, they can beat the Red Sox when it counts.

The Red Sox ran their top three starters out — Daisuke Matsuzaka, Josh Beckett and Curt Schilling — and lost all three games to the Yankees this week. Worse, they lost because they were outpitched in three games that, by Yankee standards, were relatively low-scoring.

The Yankees scored just 14 runs in the three games, nearly four below their average on the season, and never score more than five in a game. By the standards they have established, New York should have expected to lose one or more of those games; they don’t often win when they score five or fewer runs.

Boston’s problem was that it scored just six runs against the Yankees, and all of those were in the first two games. On Thursday, they got just one hit in seven innings off starter Chien-Ming Wang. On Wednesday, they touched Roger Clemens for only one hit in six innings. Even a healthy Manny probably wasn’t going to make any difference.

But great pitchers win because they make whatever the offense gives them stand up. Give a great pitcher one run, and he’ll hold the other guys to none; give him four, and he’ll hold them to three. That’s what the Yankees did. It’s what the Red Sox pitchers have to do.

The bad news is that Boston may have to face the Yankees again in October, when the games really count. The good news is that they have only three more games against them during the regular season and a whole lot of games against Baltimore, Toronto and Tampa Bay. The pitching that wasn’t quite good enough against the Yankees will be more than adequate against those opponents.

The good news for fans is that the final three games between baseball’s two marquee teams, to be played in Fenway on Sept. 14-16, will have a lot more juice to them than the three games just concluded. When these three began, the Yankees were eight games out of the AL East lead and two games behind the Mariners for the wild card.

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Very little has gone right this year for the Yankees, but this week they got the perfect storm they needed to inject themselves back into the thick of the postseason maneuvering. Their pitching got healthy, the Red Sox misplaced their offense, and the Mariners had a disastrous series against the AL West-leading Angels.

The Mariners will get their shot at the Yankees in a three-game series beginning on Labor Day in New York. But the M’s have a tough road down the stretch — Cleveland, the Yankees, Detroit and the Angels — and they also have Jeff Weaver, and he used up all his great moments last year in the service of the Cardinals. The Yankees needed a perfect storm to take command of their playoff fate; the Mariners need a miracle.

Figure that New York will soon be in control of the wild card and the last big moment of the regular season will be those three games in Fenway. It will help the Red Sox if Manny is back in the line-up, but the group that really has to prove itself is the pitching staff.

“We’re going to do as well as we’re pitching, and right now our pitching is terrific,” Yankee manager Joe Torre said after the Yankees shut out Boston 5-0 on Thursday.

It’s up to Boston’s pitchers to give their manager, Terry Francona, reason to steal that quote.