PORT ST. LUCIE, Fla. -- Left-hander Jon Niese rolled through his final Opening Day tuneup on Wednesday, striking out seven over 4 1/3 innings of the Mets' 6-2 win against the Astros.

Slated to start Opening Day against the Padres at Citi Field on Monday, Niese struck out three of the four batters he faced in the first inning, then rolled through the rest of his outing before stepping off the Tradition Field mound for the last time this spring. The left-hander gave up two hits and walked two.

"I felt good," Niese said. "Early in the spring, I really didn't feel like I had all my pitches going at one time, but today I felt like I had everything going -- especially the curveball. I felt like for the most part I could control it, throw it for a strike and throw it in the dirt when I wanted to. Overall, my arm felt good and I'm ready to go."

Against Astros starter Edgar Gonzalez, the Mets rallied for an early run when Jordany Valdespin singled to lead off the first inning, Collin Cowgill was hit by a pitch, Ike Davis singled and Marlon Byrd hit into a run-scoring double play. The Mets struck for two more runs in the third inning on Byrd's ground-rule double.

Byrd later added a solo shot against Astros reliever Xavier Cedeno to put the Mets up by four. Valdespin, who will make the Mets' Opening Day roster at least as a utility man, and possibly as the starter in center field, finished 2-for-4 to raise his Grapefruit League average to .333.

Up next: Once considered an Opening Day afterthought, second baseman Daniel Murphy is now scheduled to make his Grapefruit League debut Thursday, when the Mets play a 1:05 p.m. ET game against the Nationals (watch on MLB.TV). Murphy has been battling a strained right intercostal muscle since mid-February, but finally appears on track for the opener. With Murphy at second, prospect Domingo Tapia will start Thursday's game in Viera opposite Nationals left-hander Gio Gonzalez.