Flushing, NY (Best E Casino) - Seattle pitcher Felix Hernandez was helped off the field with a sprained left ankle in the fifth inning of Monday's 5-2 win over the New York Mets.

It was shaping up to be a banner night for Hernandez, who clubbed his first major league homer, a grand slam off Johan Santana in the second inning. That gave the Mariners a 4-0 lead. He left with Seattle ahead, 5-1.

It marked the first home run by a pitcher in Mariners history, and the first grand slam by an American League pitcher since Cleveland's Steve Dunning did it versus Oakland's Diego Segui on May 11, 1971.

However, with Carlos Beltran on third and two outs in the fifth, Hernandez uncorked a wild pitch with Ramon Castro batting. The ball got by catcher Jeff Clement. Hernandez attempted to cover home and block the plate, but Beltran slid in at full speed with his momentum twisting Hernandez's ankle and hitting his right knee.

Hernandez winced and limped in pain, but even after meeting with medical personnel insisted on trying to throw a practice pitch. After doing so, Hernandez had to be helped off the field, and he was replaced by Roy Corcoran.

"When I threw one pitch, they told me to get out of here," Hernandez said. "You know I'm not going to come out if it wasn't too bad."

However, x-rays were negative and Hernandez isn't expected to miss a start.

"We just hope we can get him back out there as soon as possible, but he's already saying he's not going to miss a start," Mariners manager Jim Riggleman said. "Rick Griffin, our trainer, is pretty encouraged he may miss a couple of days off his start, but he's feeling pretty good about it so far."

Hernandez departed after allowing two hits and a run over a season-low 4 2/3 innings. His record stands at 6-5 with a 2.83 ERA this season.