The New York Mets, who just 10 days ago were putting the finishing touches on one of the biggest late-season collapses in recent baseball history, continued their recovery by defeating the Arizona Diamondbacks and hard-throwing Randy Johnson, 8-4, tonight to win Game 1 of the National League first-round series.

New York second baseman Edgardo Alfonzo hit two home runs, including a grand slam in the top of the ninth off reliever Bobby Chouinard, to give the Mets their first postseason win since 1988, when they lost the National League Championship Series to the Los Angeles Dodgers.

Alfonzo blossomed this season after moving from third base to second base, hitting .304 with 27 home runs and 108 RBI. He provided a two-run homer in the first inning of the Mets' one-game playoff victory against the Cincinnati Reds Monday night that ensured the wild-card berth, then delivered a solo shot off Johnson in the first inning tonight.

Arizona seemed to have all the advantages heading into tonight's game. The club was well-rested, having clinched the NL West title on Sept. 24, and was starting Johnson, the game's most-feared pitcher. The Diamondbacks were baseball's hottest team in the second half of the season and, with the second-best record in the National League, had home-field advantage for the first round of the playoffs.

The Mets, meantime, did not leave Cincinnati until late Monday night after defeating the Reds. They were coming off an emotional, late-September stretch in which they squandered a four-game lead in the race for a wild-card berth by losing seven straight, only to recover to make the playoffs.

But the Mets showed little signs of fatigue, even against the 6-foot-10 Johnson. After Rickey Henderson flew out to center field to begin the game, Alfonzo launched an 0-2 pitch an estimated 422 feet into the left-center field seats.

Henderson walked to lead off the third inning, then stole second. After Alfonzo struck out, first baseman John Olerud homered to right field, becoming the first left-handed hitter to go deep off Johnson since Sept. 23, 1997.

The combination of Johnson's height, high-90s velocity and three-quarters delivery make it difficult for left-handed batters to see pitches. So dominant has Johnson been against left-handed batters that most remain on the bench when he pitches. Just seven left-handed hitters faced Johnson in 1999, generating just nine hits -- eight singles and a triple -- in 87 at-bats for a .103 average.

Mets Manager Bobby Valentine benched left-handed hitting outfielder Darryl Hamilton and switch-hitting Roger Cedeno, who earlier this season homered right-handed against Johnson, but left Olerud and fellow left-handed hitter Robin Ventura in the lineup.

"He's the toughest lefty to face for any left-hander," Ventura said before the game. "All you can do is just go up hacking and hope to get the bat on it."

Ventura led off the fourth with a double, moved over to third on Shawon Dunston's single, then scored before Johnson could field a high chopper by Rey Ordonez.

The Diamondbacks kept the game close. Tony Womack tripled to lead off the bottom of the third, then scored on Jay Bell's sacrifice fly. In the fourth, Erubiel Durazo, the former Mexican League star who was signed last December and replaced the struggling Travis Lee in July, homered in the fourth to cut the lead to 4-2.

Bell singled to lead off the sixth for Arizona. Then Luis Gonzalez followed with a blast to right estimated at 452 feet to tie the game at 4-4. The Mets loaded the bases in the ninth. Ventura singled to lead off the inning, then advanced to second two batters later when Ordonez singled. Johnson walked outfielder Melvin Mora, then was lifted for Chouinard.