New York Mets closer Billy Wagner needs elbow surgery that likely will sideline him through the 2009 season.

The five-time All-Star has been out since August 3 and the Mets said today that he has a torn medial collateral ligament in his left elbow and a torn flexor pronator, which is a muscle in the forearm. The 37-year-old left-hander will have surgery later this week.

“The tear is now big enough that the doctors are recommending so-called Tommy John surgery,” Mets general manager Omar Minaya said.

When the Mets first put Wagner on the disabled list on August 5, they announced his injury as a strained left forearm. Minaya said today that an MRI that day revealed the tear but that Wagner and the team thought there was a chance he could pitch through it.

“There’s a lot of guys that pitch with tears, especially when you’re 37 years old,” Minaya said before adding, “surgery was always a possibility in case things did not get better.”

Wagner is owed $10.5 million next year, the final guaranteed season in $43 million, four-year contract with the Mets, and the team holds an $8 million option for 2010 with a $1 million buyout. Minaya thought there was a chance Wagner could return next September.

While Wagner has repeatedly said he intended to retire when this contract concludes, Minaya wasn’t certain that would be the case.

“I think if he wants to pitch, he will have the opportunity to pitch,” Minaya said.

New York began today with a two-game lead over Philadelphia in the NL East. The Mets are 22-11 in Wagner’s absence. Luis Ayala, acquired from Washington last month in a trade, is 5-for-6 in save opportunities for the Mets.

Ayala allowed an unearned run in the ninth last night. Before that, Mets relievers had not allowed a run in 23 innings since Aug. 31.

“Any guy that we run out there is not going to be a proven guy,” Minaya said.

Wagner’s injury could cause the Mets to seek a closer on the free-agent market. Francisco Rodriguez, with 55 saves for the Los Angeles Angels, would be the most attractive and costly option.

Wearing a protective sleeve on his left elbow, Wagner tested his arm yesterday with disappointing results. Between games of a day-night doubleheader against the Phillies, he went to the mound in a virtually empty Shea Stadium and faced teammate Gustavo Molina.

A wild Wagner hit the reserve catcher on the left foot with his 13th pitch and walked off the field to consult with a trainer and the Mets’ coaching staff. Wagner was 0-1 with a 2.30 ERA and 27 saves in 34 chances. He is sixth on the career saves list with 385.