There is silence, and then there is the silence that fell over Minute Maid Park on Monday night when Albert Pujols's 500-foot, three-run home run with two outs in the top of the ninth inning off Brad Lidge disappeared over the left field wall and carried Game 5 of the National League Championship Series out of the park with it.

You could have heard a pennant drop.

One instant, the Astros led by two runs and the first National League flag in the franchise's 44-year history seemed as certain as a Lidge save against the St. Louis Cardinals, the team he has owned above all others. Just one crack of the Pujols bat later, the Cards not only had a 5-4 lead, which turned into a victory just minutes later, but they have life in this series as well. Last year, the Astros won three straight here, but lost the NLCS by dropping the final two games in St. Louis. Now, they will face the same possibility. And with a traumatic memory fresh in mind: Perhaps the most feared hitter in the game had met perhaps the most intimidating closer in the sport and the result was one of the most theatrical and monstrous postseason homers ever hit.

Lidge "is probably the best closer in the game, besides Mariano [Rivera]. And he has the best slider in the game," said Pujols, who swung and missed badly on a first-pitch slider in the dirt. "All I was thinking was, 'Don't swing at the same' " low slider.

"I'm just glad my teammates got me a chance to hit with [two men on and two outs]. If anybody was going to make the last out, I wanted it to be me. Which I didn't. I'm glad I came through for my guys."

Many playoff series have momentum shifts. But this was something different. Pujols's blast, a gargantuan, tape-measure drive that would have gone entirely out of the ballpark if the roof had not been closed, was one of the seminal moments in postseason baseball in this generation -- whether the Cards come back to win the pennant or not. That one swing on a hanging 0-1 slider was an act of singular greatness by one of the best baseball players who has ever lived in a moment of supreme need by his team.

Perhaps the most stunned person in the park was Astros Manager Phil Garner, who had just visited the mound to tell Lidge not to do exactly what he did -- throw a hittable pitch to Pujols. "We didn't have to give in to him. Make your pitches. Doesn't matter if we walk him," said Garner, recounting his conversation with Lidge. "He made a bad pitch."

And how does it feel, came the inevitable question for Garner. "Well, it's terrible. You're high as a kite one minute."

In addition, as if anything needed to be added, Pujols's homer trumped a 338-foot, three-run shot by Houston's Lance Berkman in the seventh inning, which was tucked neatly into the left field corner where the infamous Crawford Box cheap seats turn normal fly balls into home runs. If Berkman's homer, which gave Houston a 4-2 lead, was the humblest of potential pennant-winning blows, then Pujols's rebuttal was one of the most stunning -- both in drama and distance -- that anyone has ever seen. In the summer of '04, the home run derby before the all-star game was held here. Most of the game's musclemen tried to hit jacked-up balls as far as they could. None, that day, hit a ball further than Pujols's launch that traveled over the 362-foot sign in left, over the arches, over the concrete wall above the bleachers and then above the railroad tracks -- yes, the railroad tracks -- on which the Astros silly/charming mascot of a train runs after Houston home runs. For Berkman, it blew its whistle and ran its run.

After Pujols's homer came within 15 yards of conking the darn train, the vehicle sat still and silent -- the same posture as virtually everyone in the Astros crowd of 43,470. If you had listened closely enough, you might have been able to overhear whatever former president George H.W. Bush, an ardent Astros fan, said to the former first lady in their box seats. An inning before, they'd been sharing a quick celebratory kiss -- caught on the jumbo scoreboard. Luckily, no such picture -- with its lip-reading possibilities -- was shown after Pujols the Mighty had prevailed.

If the Astros eventually blow what was a three-games-to-one NLCS lead, and they well may, then the real question for Lidge and his Astros will be, "How on earth could you walk Jim Edmonds with Pujols on deck?"

Certainly that was what dominated Garner's thoughts. "The mistake we make is walking Edmonds. You can't walk him. And Brad knows that. That was a mistake."

As this NLCS precedes, the Cards have gotten to see Lidge more and more. "We've faced him every night [in Houston]. You get more familiar with him," said David Eckstein, who began the two-out, none-on rally -- following two strikeouts -- with a single to left field.

Until Pujols arrived, it seemed that this game was merely the acting out of a World Series matchup that the baseball fates have clearly ordained. After Berkman's homer, the Astros, a team that has never been to a World Series in its 44 years, seemed almost certain to meet the Chicago White Sox, the franchise that has not won a World Series in 88 years. Now that's exactly the sort of symmetry that the sport and its fans love.

Now, all of that is in question. The Astros can comfort themselves that the only way they can squander this pennant is if the 100-win Cards can win Games 6 and 7 despite facing back-to-back 20-game winner Roy Oswalt and Roger Clemens.

However, the Cards have an ace of their own, Mark Mulder, ready for Game 6. As for Game 7, the Cards may have to settle for Matt Morris, who has been a mediocre starter the past two postseasons. On the other hand, Clemens's ERA in this postseason has been 4.50. Given how the accumulated innings of this long season have worn him down, that may be a more accurate evaluation of his current stature than the gaudy 1.87 ERA he posted this season.

Still, in October, baseball seems to take on a fantastical life of its own, complete with wildly improbable doings -- like last season's Yankees-Red Sox ALCS classic -- that defy our preconceptions of what is possible.

Perhaps Pujols had to show himself at his most magnificent, and do it head-to-head against the Cards' main nemesis Lidge, so that this series could head back to St. Louis. And a culmination that is avidly awaited yet, after this night's inspired foolishness, impossible to imagine.

Albert Pujols blasts a three-run homer off Astros closer Brad Lidge with two outs in the ninth inning.