MIAMI — Top New York Mets pitching prospect Jonathan Niese will be recalled from Triple-A New Orleans to make his major league debut in the heat of the playoff race Tuesday against Milwaukee.

Niese will take the rotation spot left vacant when right-hander John Maine was placed on the 15-day disabled list a week ago because of a bone spur in his right shoulder.

"We think very highly of Jonathan Niese," vice president for development Tony Bernazard said Sunday. "He's a 21-year-old that we expect to be an important member of this organization.

"You have to perform at some point, and it happens to be Tuesday against a very good team. Let's see what he has. We'll find out a lot about where we're at with him in the next month."

Niese was a seventh-round draft pick in 2005. The right-hander went 5-1 with a 3.40 ERA in seven starts for New Orleans.

The NL East-leading Mets also need to bolster their shaky bullpen, and closer Billy Wagner, sidelined since Aug. 3 with a strained elbow, is scheduled for a bullpen session Monday in New York.

If it goes well, the next step might be for Wagner to pitch in a game for the Mets' Class A affiliate in Brooklyn.

"He's improving," Bernazard said. "He's feeling much better."