NEW YORK -- There was a huge sigh of relief inside the visiting clubhouse on Monday night after X-rays taken on right-hander Felix Hernandez's left ankle were negative.

Almost two hours after being helped off the field at Shea Stadium, Hernandez said there was no doubt in his mind that he would be able to make his next start, which would be on Sunday afternoon against the Padres in San Diego.

"I'm going to pitch next time," Hernandez said. "I'll be there."

Actually, there's still a chance that the ankle won't improve as quickly as Hernandez wants it to, but the fact that he could even be so bold to say he would pitch in five days was a welcome sign after he appeared to be seriously injured during a play at home plate in the fifth inning, ending what had been a sensational night all the way around.

Three innings earlier, Hernandez smacked a grand slam off fellow Venezuelan star pitcher Johan Santana, giving the Mariners a 4-0 lead. Needing just one more out to qualify for his seventh victory and enhance his chances of being selected to the American League All-Star team for the first time in his career, Hernandez threw a pitch to Ramon Castro into the dirt and it bounced several feet away from catcher Jeff Clement.

Carlos Beltran, who led off the fifth inning with a double and stole third, gambled and tried to score the Mets' first run of the game and cut into Seattle's 5-0 lead.

The runner and pitcher arrived at the plate about the same time. Beltran slid and upended Hernandez, who hobbled away from the plate, grimacing. He finally went to the ground as the Mariners' training staff sprinted out of the dugout to check on him.

"I didn't see what happened," interim manager Jim Riggleman said. "I was watching Clement and thought we had a chance to get an out. But the transfer didn't happen, and once Beltran slid in, I couldn't tell what happened."

Hernandez finally got to his feet and tried to continue. But he made one practice throw and winced in pain.

"When he got up and walked toward the mound, he wasn't walking that bad," Riggleman added. "I thought he might be all right and told him to take it easy on a couple of throws. As soon as he landed [on the first throw], I knew he wouldn't be able to continue."

Hernandez was helped off the field.

"You know, I'm not going to come out if it's not too bad, but it was bad," Hernandez said. "When I went in for the X-ray, I said, 'I hope it's not bad.'"

The early departure also ended a streak of 41 consecutive starts of pitching at least five innings, the third-longest active streak in the Majors and the third longest in franchise history.

"The news is pretty good, a slight sprain, and we hope to get him back out there as soon as possible," Riggleman said. "[Head athletic trainer Rick Griffin] is pretty encouraged. Felix may miss a couple of days before his next start. With the X-ray being negative and an off-day coming up [Thursday], we have a chance to move his next start toward the other end.

"The disabled list is not something we are thinking about right now, but sometimes, when it gets tender, in a few days you might have to re-evaluate that."

Having him available for the final Interleague game of the season just might help the Mariners.

After all, he's the only Mariner to hit a grand slam this season.

"I closed my eyes," Hernandez joked.

It was the first grand slam by an American League pitcher since Cleveland's Steve Dunning hit one against the Athletics on May 11, 1971. That slam was hit off right-hander Diego Segui, who six years later would throw the first pitch in Mariners franchise history.

There have now been 14 home runs by AL pitchers in Interleague Play, including two this season, the other being hit by Indians left-hander C.C. Sabathia.

Before Monday, the Mariners had been one of five AL teams without a home run by a pitcher. Now the Angels, Twins, Yankees and Athletics are on the short list.