The Boston Red Sox are moving Daniel Bard to the bullpen — temporarily, at least.

With rain washing out Bard's scheduled start against the New York Yankees on Sunday night, manager Bobby Valentine said Bard will skip his turn in the rotation and be available in relief. But when the Red Sox need a fifth starter, it will be Bard.

"As the plan is now, he's our fifth starter," Valentine told reporters Sunday after the postponement.

A day after the Yankees overcame a nine-run deficit with back-to-back seven-run innings to beat Boston 15-9, the finale of their three-game series was postponed by rain. The Red Sox called the game about five hours before the scheduled 8:05 p.m. first pitch — no doubt because of rain that was falling all day and expected to continue through the night.

But it didn't hurt that the Red Sox could use the day off.

"It's been a tough week. If I had to rate them all, this is one of the toughest," Valentine said Sunday. "When you're 4-10, it's not easy to say that everything is going perfectly. But I think they're good players, high quality, and we're going to win a lot of games."

Bard did well as the setup man last year, but after closer Jonathan Papelbon signed with Philadelphia the Red Sox opted to bring in Andrew Bailey for the ninth inning and move Bard into the rotation. Now that Bailey is injured — and Alfredo Aceves and Mark Melancon have struggled — the call for Bard to take over as closer is growing louder.

Valentine said everything would be considered.

"I don't know that there are changes right now that we're ready to make," he said.

Bard has made two starts, one bad and one better, but he lost both and has a 4.63 ERA so far this year. Valentine said he would like to use Bard in the eighth inning because he's comfortable with the role.

Jon Lester is already in Minnesota to start Monday night's game against the Twins, and he'll be followed in the rotation by Josh Beckett, Clay Buchholz and Felix Doubront. Bard's next turn would be Friday.

The Yankees were expected to push the rotation back a day, with scheduled Sunday starter CC Sabathia going Monday instead at Texas and Hiroki Kuroda to face Yu Darvish on Tuesday.

The Yankees pounded the Boston bullpen for seven runs in the seventh inning and seven more in the eighth, their biggest rally after a nine-run deficit since April 18, 1950, when they trailed the Red Sox 9-0 after five innings and went on to win 15-10. The Detroit Tigers rallied from an 11-1 deficit to beat the Washington Senators 18-12 on June 12, 1938.

"To come back in the 7th inning being down 9-nothing to the Red Sox, to be able to get the win, that's a big win for us," said Nick Swisher, who hit a grand slam and had six RBIs. "That's all I can really say. I really don't know what else to say."

The Red Sox went 7-20 in September to miss a wild-card spot by one game, leading to a tumultuous offseason in which general manager Theo Epstein and manager Terry Francona departed. Valentine replaced Francona, but the team is now 4-10 in his tenure and the Fenway fans were booing him more loudly with each trip to the mound on Saturday.

Afterward, he was asked if he had any regrets about leaving the broadcast booth to take the job.

"This is all a challenge," he said. "This is my job. If they said it was only going to be for the good days, I probably wouldn't have come. The challenges are great."

Because Sunday night's game was scheduled to be on ESPN, Francona was supposed to be in the booth to analyze his former team. The rainout saves the Red Sox from that awkward situation.

It also delays the Boston debut of newly acquired outfielder Marlon Byrd, who was traded to the Red Sox from the Chicago Cubs on Saturday night. Byrd was scheduled to start in center field as Boston tries to fill in for the injuries to Carl Crawford and Jacoby Ellsbury.

Valentine tried to be optimistic about the fact that Byrd, a 2010 NL All-Star, has just three hits in 43 at-bats so far this season.

"He isn't hitting right now; that's the good news," Valentine said, "which means he's saved up all his hits for us, which is a good thing for him to do."

The Red Sox also placed OF Jason Repko on the 15-day disabled list and said they would bring up 1B Lars Anderson from Triple-A.