ATLANTA – At last, Willie Randolph can light up that victory cigar. And fittingly, he has Pedro Martinez and Carlos Beltran to thank for it.

Martinez pitched a two-hitter, Beltran hit a go-ahead homer, and the Mets finally won their first game of the season yesterday, overcoming John Smoltz’s 15 strikeouts in a 6-1 win over the Atlanta Braves.

Before the season, star catcher Mike Piazza gave Randolph a cigar to smoke in celebration of his first victory. But the rookie manager had to wait seven long days as the Mets struggled to an 0-5 start – their worst since 1963.

“I’ve got it in my bag and I’m definitely going to smoke it when we get home,” Randolph said, smiling.

Boosted by the victory, the Mets now head back to New York for their home opener today against Houston.

The Mets trailed 1-0 before Beltran’s two-run homer chased Smoltz in the eighth. Cliff Floyd and David Wright connected later in the inning, and Martinez retired his final 16 batters in his fourth career two-hitter.

“That was the best pitching I’ve ever seen in my career,” Mets first baseman Doug Mientkiewicz said.

Martinez struck out nine and walked only one. After the bullpen cost him a win on opening day in Cincinnati, the Mets’ new ace finished this one himself for his 43rd career complete game.

“Pedro said, ‘I’m not coming out,’ ” Randolph said. “That’s just the kind of warrior he is.”

Martinez was signed to a $53 million, four-year deal in the offseason to give the team a stopper – and that’s exactly what he did. After the last out, Randolph received hugs and handshakes in the dugout.

Smoltz tied his Atlanta record for strikeouts and led 1-0 through seven innings. But Jose Reyes led off the eighth with a single and moved up on Miguel Cairo’s sacrifice before Beltran drove a 2-1 pitch over the right-field fence.

Smoltz pitched 7 1/3 innings, giving up eight hits and two runs with no walks. He set the Atlanta record with 15 strikeouts against Montreal on May 24, 1992.

“It’s not a good sign going into a game 0-5 and facing that dude,” said Floyd, who struck out in each of his three at-bats against Smoltz before hitting a home run off reliever Tom Martin. “It wasn’t fun.”

Beltran’s shot seemed to relax the Mets. Held to a combined four runs while never leading in the first two games of the series, they added three more in the eighth and one in the ninth to break the game open.

After Floyd’s homer, Mientkiewicz followed with a double off the wall to chase Martin. Wright hit a two-run shot off Roman Colon for a 5-1 lead. Beltran added a run-scoring single in the ninth off Jorge Sosa.