LAKELAND, Fla. -- New York Mets reliever Tim Byrdak will undergo surgery Tuesday morning to repair torn meniscus cartilage in his left knee and will miss approximately six weeks, general manager Sandy Alderson said.

Meanwhile, teammate David Wright received an "ultrasound-guided" cortisone shot to address left-rib cage discomfort, also after an examination at the Hospital for Special Surgery in Manhattan, on Monday.

Wright injured a left rib-cage muscle during an infield drill early in camp and has yet to appear in a Grapefruit League game.

"Basically what the doctors have told us is he had essentially plateaued -- there was a little bit of soreness, not a great deal -- but that this will accelerate the recovery process," Alderson said.

An MRI of Wright's rib-cage area did not reveal any structural damage, a team official said.

Byrdak was projected to be the lone left-handed reliever in the team's Opening Day bullpen, leaving a major void. Alderson confirmed Byrdak is expected to open the season on the disabled list.

"Obviously this will impact our left-handed relief," Alderson said. "We'll just have to evaluate things as we go forward. But I would suspect that Byrdak would not be available to us for some portion of the regular season. We'll have to accommodate that."

The Mets desperately needed Byrdak on the roster because they do not have another bona fide lefty specialist in camp. Josh Edgin, who has not appeared above Class A, was moved from minor league to major league camp effective Monday, Alderson said.

Alderson and manager Terry Collins both indicated the Mets will carry one left-handed reliever in their Opening Day bullpen in spite of Byrdak's injury. Unless Edgin makes an enormous leap, the front-runners would be veterans Garrett Olson and Chuck James. Daniel Herrera and prospect Robert Carson also are in camp. Alderson said he will decide within two days whether to sign free agent C.J. Nitkowski, who has not appeared in the majors since 2005.

Byrdak said his injury first surfaced during the offseason.

"It was something, working out in the offseason, there was a little discomfort," Byrdak said before departing for New York. "I actually felt it when I went to sit on the couch one day. I went to put my foot underneath me and I said I really didn't feel right. But there was no injury, no pop, no sudden movement that tweaked it. It's been something kind of nagging around. I was pitching with it this whole time. It's still kind of there. I sought treatment for it and it wasn't really responding to the treatment."