NEW YORK — One moment, Felix Hernandez was rounding the bases in glee after hitting the first grand slam by an American League pitcher in 37 years.

A few innings later, he was spiking his cap to the ground in frustration after being injured.

Hernandez hit a stunning grand slam off Johan Santana, then departed with a sprained ankle before he could qualify for a win in the Seattle Mariners' 5-2 victory over the New York Mets last night.

Facing a fellow ace from Venezuela, Hernandez connected off Santana (7-6) with two outs in the second inning to give Seattle a 4-0 lead.

"My approach? Just swing. I closed my eyes," said Hernandez, who figured it was his first home run since Little League. "I was happy and I was thinking that's all I need — four runs."

The opposite-field shot to right-center was the first home run by a pitcher in Mariners history, and the first slam by an AL hurler since Cleveland's Steve Dunning went deep against Oakland's Diego Segui on May 11, 1971, according to the Elias Sports Bureau.

"He had a pretty good swing," said Santana, who allowed five runs — one earned — and seven hits in seven innings. "The pitch was out of the strike zone, it was up like it was supposed to be, and all of a sudden the ball leaves the park. There's nothing you can do about it."

Three innings later, Hernandez sprained his left ankle while covering home plate on a run-scoring wild pitch. Carlos Beltran slid hard into the feet of Hernandez, who left the game one out short of being eligible for a win. After trying a painful warmup pitch, he had to be helped to the dugout by trainers.

Later, Beltran said he called Hernandez to check on him.

"It happened so fast," Beltran said. "I wasn't really watching anything except home plate. After I watched the replay, I saw that he was blocking the plate and I caught him with my spikes."

X-rays were negative and Hernandez expects to make his next scheduled start.

"Sure, I'll be there," he said.

Ryan Rowland-Smith (2-1) struck out three in two perfect innings, and Arthur Rhodes earned his first save since 2006 with Philadelphia.Diamondbacks 2, Red Sox 1: Dan Haren allowed two hits over seven shutout innings and outpitched Josh Beckett as Arizona beat host Boston. Haren (8-4) walked one and struck out five. Arizona broke a scoreless game in the seventh on Chris Young's RBI double and Chris Snyder's run-producing groundout. Beckett (7-5) gave up two runs and five hits in eight innings, striking out eight.

Brewers 4, Braves 1: Ben Sheets gave up four hits in a dominant complete-game performance and Mike Cameron hit a two-run home run in the second inning as Milwaukee beat host Atlanta. Sheets (9-1) retired the final 16 batters for his NL-leading third complete game. He struck out seven, and did not walk a batter.

Angels 3, Nationals 2: Garret Anderson's eighth-inning single drove in the go-ahead run for visiting Los Angeles, which took advantage of two Washington errors. John Lackey (5-1) allowed six hits and two runs — one earned — in eight innings, striking out six and walking one. Francisco Rodriguez pitched the ninth for his major league-leading 31st save.

Royals 8, Rockies 4: Brian Bannister picked up his third straight victory and Mark Teahen hit a three-run homer in a four-run first inning as host Kansas City beat Colorado. Bannister (7-6) gave up three hits and three runs, all unearned, while striking out five in seven innings.

NOTES

Red Sox: First baseman Kevin Youkilis left last night's game against Arizona prior to the top of the fifth inning after getting hit under the right eye by Mike Lowell's one-hop throw during infield warmups. Youkilis, who had a bruise and bump under the eye, was taken for "a precautionary CT scan," the team said.

Cardinals: Cardinals pitcher Mark Mulder was scratched from a scheduled injury rehabilitation start with Triple-A Memphis last night due to back stiffness. Mulder, recovering from a pair of operations on his left shoulder, is day to day, the team said in a release.

Dodgers: Waipahu alum Jerome Williams was signed by Los Angeles yesterday. Williams, who was pitching for the Long Beach Armada of the independent Golden Baseball League, is scheduled to report to the Inland Empire 66'ers, the Dodgers' A club.

Nationals: First baseman Nick Johnson will undergo surgery today on his injured right wrist and may not return this season, Washington general manager Jim Bowden said.