The reality of their perpetually dire situation has never bothered the New York Mets. So as the Mets awoke this morning, one eye at a time, to find themselves still alive after Sunday's intoxicating 4-3, 15-inning victory over the Atlanta Braves in Game 5 of the National League Championship Series, they would probably tell you the morning-after hangover was well worth it.

While members of both teams began the process of trying to digest what occurred Sunday over the course of 15 innings, 482 pitches and 5 hours 46 minutes--the longest postseason game in major league history--there is also the matter of Game 6 to consider.

It will take place Tuesday night at Atlanta's Turner Field, where the Mets have won only once in the past two years and where last week the Braves stormed to two straight victories, adding a third Friday night at Shea Stadium that gave them a seemingly safe 3-0 lead.

Four outs from elimination on Saturday, three outs away on Sunday, the Mets won both games to make it to this point. Sunday's cathartic victory, after the Braves had taken a 3-2 lead in the top of the 15th, came on Shawon Dunston's single, two walks, a sacrifice bunt and Robin Ventura's blast off Braves rookie Kevin McGlinchy. The hit was ruled a single even though it left the park because Ventura never made it to second base.

"It was surreal," said Mets pitcher Orel Hershiser, one of a record 15 pitchers and 44 players who appeared in the marathon contest. "It was right up there with the Kirk Gibson home run, the Bucky Dent home run and the Bill Buckner ground-ball game. It will be on all the highlight tapes with them."

"It was getting to the point," Mets center fielder Darryl Hamilton said, "where your stomach is coming out of your guts."

Four days ago, from the bottom of a 3-0 hole, this is what the Mets were looking up at: To climb out, they would have to beat, in order, John Smoltz, Greg Maddux, Kevin Millwood and Tom Glavine. The 1997 Cy Young winner, the best pitcher of his generation, the toughest pitcher to hit this season and the winningest left-hander of the 1990s.

The Mets are halfway there, having survived Smoltz and Maddux.

But as the Mets are well-aware, no team has ever come back from a 3-0 series deficit in baseball history. None of the previous 23 teams had even survived to see a Game 7. In fact, until Ventura's dramatic over-the-fence single finally gave the Mets the victory in the bottom of the 15th, the 1998 Braves had been the only other team in that predicament to force a Game 6.

This is what the Mets face now, having drained their available resources and tapped into the emergency reserve on Sunday: They will send left-hander Al Leiter to the mound Tuesday night on three days' rest for the second time in his career, and the first since 1994. He will be opposed by Millwood, who will be pitching on a full five days' rest.

With the Braves still in command of the series, Manager Bobby Cox resisted the temptation to use Millwood in the 15th inning Sunday to close out a 3-2 lead, even though that left the Braves' fate in the hands of McGlinchy, a rookie who had never pitched above Class A before this season.

"We could have done a lot of things differently, but I didn't want to do it," Cox said. "With the weather and the one-run lead, it wasn't worth bringing in Millwood and moving the rotation around. I'd rather be given the opportunity of being on our own field with a good mound."

If the Mets somehow beat Millwood to force a Game 7--and nobody dares question that they might--they likely would pitch Rick Reed, also on three days' rest, against Glavine.

The Mets might also be without all-star catcher Mike Piazza, who over the course of the two weekend games at Shea Stadium was steamrollered by Bret Boone, whacked by the follow-through of two Braves batters on two parts of his left hand and, finally, in the 13th inning Sunday, hit on the left forearm by Keith Lockhart as Piazza tagged him out at home plate.

Piazza left the game after striking out in the bottom of the 13th with what was diagnosed as a strained left forearm. Piazza's availability might be a game-time decision.

But the Braves have their own set of problems to worry about. Like the Mets, they used every reliever Sunday, leaving them shorthanded for Game 6.

Perhaps more troublesome is the Braves' lack of offense. Even if Millwood, against whom NL hitters batted just .202 this season, pitches another gem along the lines of his one-hitter in Game 2 of the first-round series against Houston, it won't matter if the Braves can't figure out a way to score.

The first six hitters in the Braves' lineup (Williams, Boone, Chipper Jones, Brian Jordan, Ryan Klesko and Andruw Jones) are hitting a combined .192, and in Sunday's game the Braves stranded a postseason record 19 base runners.

Postseason slumps are nothing new to the Braves: In their 17 NLCS games from 1997 to '99, they are averaging just 3.1 runs per game.

"Right now, it's a problem," Braves hitting coach Don Baylor said. "We're not taking good swings. We're swinging at balls."

Then there is the cumulative emotional effect of these last two losses. Saturday night, the Braves were four outs away from advancing to the World Series before John Olerud's two-run single off closer John Rocker in the eighth inning. On Sunday, they were three outs away after Lockhart's triple.

"You can't lose sight of the big picture," Maddux said. "We came up short, but we still have life. But it's a good thing we won the first three games."