Updated

NEW YORK (AP) — Carlos Beltran will begin a rehabilitation assignment Thursday and could be manning center field for the New York Mets before the All-Star break.

Beltran has been out all season after having right knee surgery in January. He has been working out at the team's spring training facility in Port St. Lucie, Fla. General manager Omar Minaya saw him play Sunday and was pleased with the five-time All-Star's progress.

"It's very encouraging to hear he's doing extremely well," manager Jerry Manuel said Tuesday before the Mets played Detroit. "He's very excited about getting back and playing, and he's in a hurry to help the team."

But Beltran will have to prove at Class-A St. Lucie that he can go all-out and stay healthy before he is activated from the disabled list. Beltran has expressed an interest in returning to the Mets by the time they play the Florida Marlins in Puerto Rico, his homeland, at the end of June, but Minaya said that is unlikely.

"We need to see that he will be able to play up here and be able to play and play comfortable and be able to perform and be able to bounce back the next day," Minaya said. "He's got to be able to help this team in the phases of fielding, running, hitting and also he's got to be able to do it on a regular basis."

Minaya acknowledged that Beltran, who missed 2½ months last summer with a bruised knee, has a limp when he runs but he attributed it to the large brace the three-time Gold Glove winner is wearing. Minaya said it is most likely Beltran will return after the All-Star break, which is July 12-14.

Beltran is in the sixth season of a $119 million, seven-year contract. His offseason surgery was a big disappointment for a club coming off a 70-92 season that was wrecked by a slew of key injuries. He even ended up in a dispute with the team over the timeline of approval for the operation.

This season the Mets have surged to second place in the NL East at 39-30 entering Tuesday's game, and Angel Pagan, subbing in center field, has played a big role in the team's success.

Pagan has hit .325 since May 5 and is batting a team-high .296 with four triples, four homers and 31 RBIs. He stands to lose the most playing time when Beltran returns, but he's not worried about that.

"What happens when he comes back, I have no control of that," Pagan said. "The only thing I can control is to stay ready for whatever opportunity and to keep helping the team in any way."

Manuel said with a laugh that he prefers the problem of having to find playing time for four solid outfielders to the difficulty of cobbling together a lineup the way he did last season, when he was relying on several players who weren't ready for the big leagues.

To keep Beltran, right fielder Jeff Francoeur and left fielder Jason Bay happy Manuel said he will try to map out each week so his players know when and how they will be used. Pagan, he said, is the most versatile.

"Pagan is the guy that has the ability of all three to play in three different spots," Manuel said.

Also, the Mets said right-hander John Maine has gone for a second opinion on his sore right shoulder and they will have a report in the next couple of days.

New York also recalled right-hander Bobby Parnell from Triple-A Buffalo to take Jenrry Mejia's place in the bullpen. The 20-year-old Mejia was sent to Double-A Binghamton to work as a starter. Parnell made 68 appearances — eight starts — for the Mets in 2009.