Mets 11, Padres 2: Jon Niese pitched 6 2/3 strong innings and Collin Cowgill drilled his first career grand slam to seal it in the seventh inning as New York rolled over visiting San Diego in the season opener for both teams.

Niese (1-0), who was also 2-for-2 at the plate and knocked in a run, allowed four hits and a pair of runs while striking out four. Cowgill also had a double and Marlon Byrd recorded a pair of two-out RBI singles for the Mets, who scored their second most runs in a season opener.

Yonder Alonso belted a solo home run in the sixth and Carlos Quentin, hampered by a knee injury during the spring, had an RBI single for the Padres. San Diego starter Edinson Volquez (0-1) gave up six runs on six hits in three-plus innings, dropping to 0-5 lifetime against New York.

Ruben Tejada’s two-out double down the left field line opened the scoring in the second for the Mets, and Niese followed by serving a single over third baseman Cody Ransom for a 2-0 lead. Byrd and John Buck delivered two-out RBI singles in the third as New York stretched the lead to 4-1.

The Mets broke it open in the fourth with three runs, highlighted by RBI singles from Daniel Murphy and Byrd for a 7-1 advantage. Tejada and Buck each notched their second hits and scored for the second time on Cowgill’s line-drive home run to left field.

GAME NOTEBOOK: The Mets are 34-18 all time on Opening Day, the best percentage of any team (.654), including 34-10 in the last 44. … San Diego 2B/3B Jedd Gyorko became the 28th rookie in franchise history to start on Opening Day and he doubled in the sixth for his first major league hit. … Todd Hundley had the only other grand slam on Opening Day in franchise history for New York in 1995 at Colorado.