The Mets were impressed that Dotel came back and retired the side to keep it a one-run game.
"That gave us a chance to win the game," manager Bobby Valentine said.
"I was saying, `Let's go, we don't lose the game yet, so I've got to keep going,"' said the 23-year-year Dotel.
"I appreciate those guys, they pick me up, coming back and they win the game. If we lost this game, I'm going to feel like that's for me because I don't make the pitch I have to make with this guy. But now I'm so happy because we won the game."
Alfonzo singled in the eighth and later scored on Piazza's double-play grounder to make it 3-all. In the 10th, Alfonzo connected against Will Cunnane (2-1) for his 19th home run.
Piazza homered for the fourth straight game. The Mets won their sixth in a row against the Padres.
"I just lost my rhythm a little bit," Dotel said.
Nevin's 17th homer deep into the left-field seats on a 3-2 pitch left the Mets as one of five big league clubs the Padres included who have never thrown a no-hitter.
Coincidentally, Nevin, then with Anaheim, broke up a no-hit bid by San Diego's Sterling Hitchcock with a homer leading off the eighth inning here on June 27, 1998.
"He's got some nasty stuff," Nevin said of Dotel. "He's got no fear up there. He reminds you a lot of Pedro Martinez out there on the mound, his actions. He comes right after you. He looks like a gamer to me."
Dotel got his first two hits in the majors.
Dotel was making his ninth big league start. He allowed one hit and three runs in seven innings, struck out nine and walked three.
Dotel didn't figure in the decision in the Mets' 12-5 victory over the Padres at Shea Stadium last Wednesday because he lasted just 4 1-3 innings, allowing five runs on four hits.
"The difference between him today and when we saw him back in New York was he hit his spots," Nevin said. "After the first inning last week, he was pretty much unhittable then, too."
Piazza homered in his fourth straight game for the second time this season, the seventh time a Mets player has accomplished the feat. He tied the team record when he homered in four straight games from May 17-21.
Piazza drove a 2-2 pitch from Hitchcock an estimated 448 feet into the second deck in left-center field leading off the second for a 1-0 lead. It was the 24th homer to reach the second deck in 31 seasons of big league ball in San Diego.
Henderson hit Hitchcock's first pitch of the sixth inning deep into the left-field seats for a 2-0 lead. It was the 10th for Henderson, who played with the Padres from 1996 until being traded to Anaheim on Aug. 13, 1997.
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