Flushing, NY (Sports Network) - Felix Hernandez clubbed the first grand slam by an American League pitcher in 37 years, but then departed the contest with a sprained left ankle in Seattle's 5-2 victory over Johan Santana and the New York Mets.

Jose Lopez had two hits and an RBI for the Mariners, who opened the three-game series with their third victory in 10 games.

Hernandez departed after allowing two hits and a run over a season-low 4 2/3 innings. Ryan Rowland-Smith (2-1) struck out three batters over two innings to get the victory.

David Wright had a costly error in the second inning, for the Mets, who had won five of seven entering the series. Carlos Beltran accounted for two of New York's four hits, driving in a run and scoring once. Jose Reyes had the two other hits, both singles.

Santana (7-6) was lifted after being charged with seven hits and five runs -- one earned -- over seven innings. The lefty is 0-4 over his last four outings, and he lost for just the second time (7-2) in his career versus the Mariners.

It was shaping up to be a banner night for Hernandez, who clubbed his first major league homer in the second inning. That gave the Mariners a 4-0 lead, and it came partly due to Wright's error.

Adrian Beltre singled to lead off, and two outs later Jeff Clement singled to right. Willie Bloomquist then hit a grounder to Wright, who bobbled the ball and the bases were loaded.

Hernandez then smacked the first offering from Santana to the opposite field, over the wall in right-center field. 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.

Hernandez said he closed his eyes when he swung at the high fastball. His approach was to swing and get a base hit, but he did much more than that.

"We had a good idea of what to do," Santana said as far as pitching to Hernandez. "When he swung, he even closed his eyes, and the ball just flew off his bat."

Lopez singled in Bloomquist in the fifth, but in the bottom of the inning Carlos Beltran doubled and stole third with one out. With two down, Hernandez uncorked a wild pitch with Ramon Castro batting. The ball got by catcher Clement. Hernandez attempted to cover home and block the plate, but Beltran slid in at full speed safely, with his momentum twisting Hernandez's ankle and hitting his right knee.

"When the play happened I'm thinking I've got to find a way to score," Beltran said. "I caught him with my spike."

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."

Beltran singled in Luis Castillo in the ninth inning, but Arthur Rhodes closed the door for his first save since August of 2006. With runners on first and second, Rhodes struck out both Carlos Delgado and Damion Easley to end the game.