NEW YORK -- Jerry Manuel may spend most of his time at a baseball park, but sometimes the Mets manager feels more like a boxer.

He does his best to duck the punches that come with injuries and the loss of key players, all the while trying to stay on his feet.

"I'm kind of bobbing and weaving out there," he said. "And every now and then I get caught. Bam!"

Manuel and the Mets took a blow Monday, when they placed right-hander John Maine on the 15-day disabled list with a bone spur in his right shoulder. It is his second trip to DL this month, the first because of a mild strain of his right rotator cuff.

Maine made three starts after his return to the roster, trying to pitch through the pain. He didn't give up any runs through his first two return outings, but the righty suffered his roughest outing of the season on Saturday, when he gave up eight runs and 10 hits to the Astros. And more importantly, the pain in his arm had not dissipated.

"I was told the thing I wanted to hear -- that nothing could really make it any worse, which is why I wanted to try to pitch through it," Maine said. "It just hasn't gone away like I thought it would after all the stuff I've tried doing with it.

"It's frustrating because I want to be here, I want to help the team. But I think me not being able to 100 percent go out there, that's hurting the team a little bit."

The first attempt at a solution came Thursday, when Maine received a cortisone shot, but it proved ineffective for the righty. General manager Omar Minaya said giving him time off to rest on the DL is the next step in the hopes that Maine will be able to return by mid-September.

Maine will go two weeks without throwing and one week without any sort of exercise, translating into at least three weeks that he will be out of the New York rotation. He is hopeful that the rest will help lessen the pain, though his first trip to the DL did not solve the problem.

"When I rested it the first time, it did feel a little better," he said. "But once I started going at it pitching, it kind of came back."

The loss has come at a critical time for the Mets, who sit just a half-game ahead of the Phillies in the National League East standings entering Monday's contest. But Minaya said the importance of Maine's health outweighed the benefits of his experience on the mound.

"Even without his best stuff, he pitched a pretty good game against Pittsburgh," Minaya said. "But the [bottom] line is we just cannot risk his long-term health in the midst of this pennant race."

To fill the vacant spot on the roster, New York activated second baseman Luis Castillo, returning from his own trip to the DL with a strained left hip flexor. The Mets have not yet named a pitcher to take Maine's spot in the rotation. Manuel said with an off-day Thursday, he does not think the team will need a fifth starter until Sept. 2, as Oliver Perez will likely pitch in Maine's slot Friday, and Minaya said the Mets will look internally for a replacement.

Minaya said it would not be out of the question to go with a long reliever like Brandon Stokes or a young Triple-A prospect like righty Bobby Parnell or left-hander Jonathan Niese.

"I feel comfortable that we'll find a way internally to get it done," Minaya said. "I'm very comfortable with our young prospects coming here and doing it."

And if one of the Triple-A pitchers is selected, Minaya made it clear that it would be for more than a one-day stint.

"I don't like bringing kids up, then sending them down for one start," he said. "This would not be for one start. If we decided we would go [with Niese], or if it was to be Parnell, he would be here through September callups."

The loss of a member of the starting rotation also had ripple effects for righty Mike Pelfrey. Manuel had discussed the possibility of giving Pelfrey rest because of the high number of innings he has already pitched this season. But while the Mets continue to hold off the Phillies, Manuel said that move is likely no longer an option.

"He has performed well, and hopefully we've gotten through the period where he needs a day or so," Manuel said. "Hopefully, he's at that part of the year where his second wind kicks in, and boom.

"We don't have, in my opinion, the luxury or wiggle room to do all the different 'give you this, give you that.' We are in the fight of our life, and we've got to go with what's best."

While Monday's news was another punch Manuel had to take and bounce back from, he was confident that his team could deal with the extra blow, and he made one thing clear: "We're still in the fight."