The Astros' Yuli Gurriel is congratulated by Jose Altuve after scoring during the fifth inning of their 4-0 win over the Yankees in Game 7 of the ALCS in Houston. (David J. Phillip/AP)

Once a precious lead is gained in Game 7 of a postseason series, everything else melts away, and all that is left, all that matters in the world, is the slow, steady, arduous counting down of outs. When the Houston Astros handed the ball to Lance McCullers Jr. in the final game of the American League Championship Series on Saturday, it was the start of the sixth inning. They held a four-run lead over the New York Yankees. They needed 12 outs to reach the World Series.

Twelve, 11, 10. Each out seemed to take an eternity to secure — 9, 8, 7 — each base runner a dire threat, every pitch a life-or-death proposition. And still McCullers stood and fired — 6, 5, 4 — until it was the ninth inning now, the Minute Maid Park crowd on its feet and building up to a hellacious roar. And finally, 3, 2, 1, the final out fell from the sky and into George Springer's glove in center field, and the Astros had a 4-0 victory, the American League pennant and the franchise's first trip to the World Series in 12 years.

The collective exhale felt like the building might come down. The home team won all seven games in the series, and nothing may have meant the difference between winning and losing as much as the fact the seventh game was here.

"With every out, I was just like, 'Keep it calm, keep calm, bring it down, bring it down a notch,' " McCullers said afterward, near the stage that had been quickly erected in the middle of the field for the trophy ceremony. Chaos reigned everywhere, family members running onto the field, confetti falling from the sky, a muffled wall of sound coming from the stands and the PA system. "This is unreal, man."

The Astros, winners of 101 games in the regular season, will face the Los Angeles Dodgers (104 wins) in Game 1 of the World Series on Tuesday at Dodger Stadium in what will be the first matchup of 100-win teams in the Fall Classic since the Baltimore Orioles (108) conquered the Cincinnati Reds (102) in 1970.

Saturday night's game, a winner-take-all contest at the end of a dramatic, back-and-forth battle between two talented teams, unfolded in more or less the manner the Astros had hoped. They waited out Yankees starter CC Sabathia — getting a break when Yankees Manager Joe Girardi was inexplicably slow in making his pitching moves — and seized a lead in the middle of the game, on solo home runs by Evan Gattis and Jose Altuve and a two-run double by Brian McCann.

"I grew up in a baseball house. I've been going to the field since I was three years old," McCann said in the Astros' champagne-soaked clubhouse. "I've lived this moment a million times with my brother in the backyard at our house in West Virginia. And it's not over. This is only step one. We get to play in the World Series, and we want to win this thing."

As they have done for most of the series, the Astros played seamless defense Saturday night. They got a huge defensive play from third baseman Alex Bregman and catcher McCann — the former throwing home with almost no margin for error to cut down Greg Bird in the fifth inning on what would have been the tying run, the latter somehow holding on to the ball as Bird slid into his mitt.

They survived the deflating feeling of seeing Aaron Judge, the Yankees' massive right fielder, leap and crash into the wall to rob Yuli Gurriel of a home run.

And despite constant reminders that it was "all hands on deck" — which carried the tantalizing possibility that Justin Verlander, later named the series MVP, might ride in from the bullpen on a white horse to close it out, 24 hours after throwing 99 brilliant pitches in the Astros' Game 6 victory — the Astros actually envisioned using just two pitchers, starter Charlie Morton and McCullers, to carry home the victory.

McCullers, the Astros' Game 4 starter, was pulling into his driveway late Friday night when his cellphone rang. It was A.J. Hinch calling. In truth, McCullers probably wasn't in the mood to speak to his manager at that moment. Only hours before, Hinch had the duty of informing a disappointed McCullers he wouldn't be getting the ball to start Game 7 on short rest — Morton would be, on full rest — and the short drive home hadn't erased the sting.

But he answered the call.

"I know you wanted to start the game," Hinch told him, as McCullers recalled. "But tomorrow when you get the ball out of the 'pen, expect to keep it — and finish this damn game."

When McCullers got to the park in the afternoon, in his mind he treated it like a start. Only this start would begin, more than likely, somewhere around the middle of the game.

Morton had done his part, carrying a shutout through the first half of the game. But when Morton's stuff showed the first signs of wavering, Hinch called to the bullpen and got McCullers warm. He gave up a leadoff single in the sixth, but retired the next six Yankees. As the crowd stood and got ready to sing and clap along to "Deep In the Heart of Texas" at the seventh inning stretch, McCullers breezed past Hinch in the Astros' dugout.

"That was my mentality," he said. "I wasn't even giving A.J. the opportunity to talk to me and tell me this or that, 'How you feeling?' — nothing. I did a fist-bump and walked right by him."

At one point, McCann, behind the plate, called for 24 consecutive curveballs from McCullers, leaning on the right-hander's signature pitch to carry them through the eighth and part of the ninth.

"Lance McCullers has some of best stuff you're ever going to see," McCann said. "He got in a groove with that curveball, and we kept it going. I told him [Friday] night I wanted to take this game and tuck it in his arms."

This was the fifth time in 18 days the Yankees, a wild card entrant into the postseason, had faced a win-or-go-home game — a grueling, harrowing reality that had both hardened and emboldened them. At one time, the Cleveland Indians seemed as unbeatable at Progressive Field as the Astros did at Minute Maid Park, but the Yankees survived Game 5 of the Division Series there, and they believed they could prevail again Saturday night.

The Astros, on the other hand, had never been so tested as they had in facing a 3-2 series deficit entering Game 6. They had held first place in the AL West every day this season after April 13 and didn't see their lead dip below 10 games after May 27. Over their final 34 games of the regular season, a time when playoff-bound teams are looking to find another gear, they played only four games against teams that finished with a winning record. They were not what you would call battle-tested, and had pretty much zero experience with playing from behind until Friday night.

"We really didn't have any games where, if we lost there'd be severe consequences until yesterday," General Manager Jeff Luhnow said. "But watching them on the flight back from New York and during [batting practice] yesterday, they knew the stakes were high, and they knew they hadn't been tested to this extent. But I also felt they had a lot of confidence."

The Astros, heavy into analytics and unconcerned with what anyone else thinks of them, do things a little differently than most organizations — a fact that has brought a measure of derision and disdain across the industry over the years, but an approach that has been validated by their 101-win season and especially what they have accomplished this month.

One thing the Astros have always done, and still do, is "piggyback" their minor-league starting pitchers at Class AA and below — using one starter for the first five innings or so, and another for the last four or so. That way, even the Astros' best young starters gain the experience of pitching in relief.

After Saturday night's win, Luhnow found McCullers, a product of the Astros' farm system, and reminded him of those long-ago piggyback nights in the minors. McCullers still had the sweat from his four-inning save running down his body, and at that moment may have finally understood the reason behind something he once resisted.

"They never liked it," Luhnow said. "But they learned how to pitch late in games."

You never know when that might come in handy.