MIAMI — The Mets are throwing caution to the wind in the middle of a pennant race by throwing rookie Jon Niese on Tuesday against the Brewers in Milwaukee. Jerry Manuel announced the long-rumored move here today, saying it was an organization-wide decision that Niese would get the nod and make his major-league debut. Niese will be opposed in the 8:05 p.m. start by Brewers left-hander Manny Parra, a 10-game winner.

Niese, a 21-year-old left-hander and one of the Mets’ prized prospects, is being promoted as part of the Mets’ September call-ups after going 5-1 with a 3.40 ERA for Triple-A New Orleans.

Niese’s strength are his two curveballs, especially the 12-to-6 version he uses as his out pitch. Manuel said Niese impressed him in spring training with a strong start in late March against the Braves.

The Mets need a fifth starter with John Maine on the DL indefinitely due to a bone spur in his right shoulder. Niese is expected to be a spot starter in September instead of a regular member of the rotation because the Mets have three off days scheduled in the first two weeks of the month.