NEW YORK -- A home run off the bat of a pitcher prompts smiles like a toddler's malaprops or a kitten with a ball of yarn. Shea Stadium smiled from foul pole to foul pole on Tuesday night. It smiled like Jose Reyes after a triple, only wider.

The bat of John Maine -- yes, Maine -- had produced a home run. Imagine that. Just the thought, without the feat, is worth a smile and a cackle. But the real thing happened in fourth inning on Tuesday night before 49,122 witnesses. And it prompted at least 49,000 smiles.

"The others," Maine suspected, "were in total shock."

One of the more prominent straight faces was worn by the man responsible. Maine never had made the 360-foot, right-angle trip around the bases before his bat created an arching 365-foot trip for the baseball. And, goodness knows, he never considered -- much less practiced -- a trot. So while Shea smiled, Maine made sure not to trip or miss a base and provide another reason for smiles.

"He didn't smile once the whole way around," Joe Smith said. "Hey, I smiled when I struck out in my one chance. Are you kiddin'? If I hit one out, I would have been doing backflips."

"I just wanted to get back to the dugout," Maine said. And there, he joined in the smiling and executed another personal first, a curtain call wave. His manager and some others thought that might have been a little much.

On this pleasant baseball evening, the Mets defeated the Pirates, 8-4, and made it look easy. It was Maine who helped create that sense and he who made it look like fun.

"It was kinda cool. Wasn't it?" Maine said.

The Mets already had scored twice in the fourth inning, providing their pitcher a 4-2 lead. Shawn Green had driven in Paul Lo Duca with a single. And, after a wild pitch, Lastings Milledge drove in Green with a single, the second of his three hits. Next was Maine, a mostly unskilled hitter with a resume to prove it. He had made himself in a proficient bunter, but there was no bunt signal before the second pitch he saw from Ian Snell and no reason to anticipate anything more than an out or, at best, a single.

Maine had been to bat 81 times -- 62 official at-bats -- in the big leagues and produced three singles and a double. Manager Willie Randolph would have been delighted if his pitcher merely avoided a double play.

"You never expect a home run from a pitcher," Randolph would say later, "even the ones who swing the bat."

On this night, though, Maine provided the first home run by a Mets pitcher since last June, when Steve Trachsel hit one against the Reds and tripled his career RBI total. And Maine made a ballpark smile and his teammates joke.

"It's just how easy it is to hit," Aaron Sele said. Such a pitcher thing to say. Or was it jealousy? Sele, an American League lifer until last season, has 72 career plate appearances, but no damage and no dingers.

"I am jealous,' Aaron Heilman said. He has no plate appearances in 47 games this season and one hit in 50 career plate appearances. His next chance to swing is tentatively scheduled for 2012.

"Ah, c'mon," Tom Glavine said. "Been there, done that." Though it was 12 years ago and hit the old place in Atlanta known as the "Launching Pad" for a reason.

No such qualifiers with Maine's. His hit was quite legit. It had carry and hang time. It landed in the loge.

His pitching colleagues actually were quite impressed. Though Randolph kidded that "He [Snell] just threw it where John happened to swing," others attributed the unprecedented show of power to the time Maine spent in the batting cage in Spring Training.

"He told me he was horrible last year," Sele said. "And I can tell you, he really work on it this spring, his hitting and his bunting. He got two [sacrifice bunts] down tonight, and he may be more proud of those than of the home run."

Maine did more than use his bat Tuesday night. He had three plate appearances because he pitched well. He limited the Pirates to five hits -- one a home run by struggling Jason Bay -- and one walk in seven innings. Maine struck out seven and won for the first time in three starts, putting his record at 11-5, the best among the Mets starters. He allowed a run in the first inning and the first of Bay's two home runs -- the second came against Guillermo Mota in the ninth -- in the fourth.

His work in his primary role was mostly overlooked on this night, though.

The Mets were pleased to win for the ninth time in their 11 games at Shea and the eighth time in 12 games since the All-Star break. But they were genuinely delighted for their comrade.

"You like to see a good guy rewarded when he's worked so hard at it," Glavine said.

"I have been working at it,"Maine said. "But it was just luck. I just swung as hard as I could. I thought he was going catch it. When it went over, I was as surprised as anyone."

So what would some of his colleagues have to do to surprise Shea Stadium as Maine had? That was a topic of discussion for a few moments on Tuesday night.

"I probably have a better chance at hitting one out that hitting a triple," Heilman said. "So ... a triple for me."

"Steal home," Lo Duca said. "But not on the front end of double steal. A straight steal of home."

Shawn Green pondered the question for a moment.

"For me?" he said. "... Hit a home run."