PORT ST. LUCIE — Jon Niese has all but locked up the final spot in the Mets’ rotation.

Jerry Manuel made that pronouncement after watching the lefty fire two scoreless innings of relief in the Mets’ 5-2 exhibition victory over the Astros.

“Jonathon Niese has been pretty impressive and he was impressive last year, the last time we called him up,” Manuel said.

Niese’s addition to the rotation would allow the Mets to use Fernando Nieve in the bullpen. Hisanori Takahashi, who can start or relieve, likely will become the second lefty in the bullpen, behind Pedro Feliciano.

Niese, who tore his hamstring tendon while covering first base against the Cardinals last August, has a 5.59 ERA in Grapefruit League action. He entered camp battling Nieve, Nelson Figueroa and Pat Misch for the fifth spot in the rotation.