Felix Hernandez, Seattle starter, became the first American League pitcher to hit a grand slam home run in 37 years, with his second inning blast helping the Mariners record a 5-2 win over the New York Mets.

Hernandez drilled a shot to right-center field off fellow Venezuelan Johan Santana with two outs in the second inning to put the Mariners in front 4-0, before leaving the game with an ankle injury in the fifth inning.

It was the first home run by a Mariners pitcher and the first grand slam home run by an AL hurler since May 11, 1971, when Cleveland's Steve Dunning connected with the bases loaded off Oakland's Diego Segui.

The Mariners ace figured it was his first home run since Little League baseball and said he was as surprised as anyone.

"I closed my eyes," Hernandez told reporters.

"I was happy and I was thinking that's all I need - four runs."

It was indeed all the Mariners needed to win, but Hernandez's historic accomplishment was marred three innings later when he sprained his left ankle while covering home plate after he threw a wild pitch.

Good swing

New York's Carlos Beltran raced home from third base on the play, sliding into Hernandez's feet.

Hernandez attempted a warm-up pitch but had to be helped off the field by team trainers afterwards, however x-rays revealed no damage.

"I didn't want to come out of the game," Hernandez said.

"Sure, I'll be there [for his next start]."

Since he pitched just four and two-third innings, Hernandez missed qualifying for a win by one out.

Santana said Hernandez just hit a pretty good pitch.

"There's nothing you can do about it," Santana said.

"He had a pretty good swing."