HOUSTON — The Houston Astros rolled through the initial portion of these playoffs like world-beaters. Upsets pervaded the field, knocking off dominant teams in Los Angeles and Atlanta and New York. But the Astros — a 106-win juggernaut in their own right — won each of their first seven games, vaulting themselves into their fourth World Series appearance in six years. They met a Philadelphia Phillies team that won 19 fewer games than them during the regular season, representing the second-largest margin between World Series opponents in baseball history.

The Astros were widely expected to cruise.

Then they dropped Game 1 on Friday night — at home, with a five-run lead on the scoreboard and their ace on the mound.

“It was a punch in the face,” Astros center fielder Chas McCormick said. “Maybe we needed it.”

Their response seemed to validate that belief.

The Astros matched up against the most dominant pitcher of this postseason and came out swinging Saturday night. Four pitches into the game, they had accumulated three doubles. By the end of the fifth inning, they had totaled another five runs. And this time, thanks in large part to an impressive pitching display from Framber Valdez, the Astros didn’t relent, securing the 5-2 win from Minute Maid Park that evened this Series at a game apiece.

It all began with Jose Altuve, who contributed a leadoff double and finished with a much-needed three-hit performance.

“It was awesome,” Astros third baseman Alex Bregman said of Altuve. “I feel like that one swing of the bat to start off the game got the crowd into it, got our dugout into it, got our offense going.”

Philadelphia’s Zack Wheeler was nearly unhittable through his first four starts of these playoffs, posting a 1.78 ERA. His 0.51 WHIP was on pace to become the lowest in postseason history among pitchers who accumulated a minimum of 25 innings. But his first pitch of this World Series, a sinker down the middle, was driven to left for a double by Altuve. His second pitch, a curveball near the heart of the plate, was driven to left for a run-scoring double by Jeremy Pena. His fourth pitch, a slider slightly up, was driven off the left-field scoreboard for a run-scoring double by Yordan Alvarez.

“That was the plan — to attack him early,” Alvarez said in Spanish. “He likes to attack hitters early in counts, but we have a lot of good hitters.”

The Astros became the first team in World Series history to begin a game with three consecutive extra-base hits. It also marked the first time in postseason history that a team notched three extra-base hits within the first four pitches of a game, according to research by ESPN Stats & Information. Only three teams have ever achieved that feat in a regular-season game over the past 20 years.

“It’s kind of everybody’s game plan against me to be really aggressive and just try to get that first pitch or hop on the fastball,” Wheeler said. “I kind of expected that. But to swing at the first two pitches? It is what it is. I just need to execute a little better.”

Wheeler completed five innings but was tagged with five runs, four of them earned. The Astros tacked on an additional run in the first on a two-out throwing error by Phillies shortstop Edmundo Sosa, and Houston then got two more on a fifth-inning homer from Bregman.

Wheeler throws his three most trusted pitches — a four-seam fastball, a slider and a sinker — at high velocities. He also throws a lot of strikes, a trait that makes him a highly effective starting pitcher. But the Astros were the second-best team in the majors this season at making contact within the strike zone and carried the third-highest OPS against fastballs.

“Everything’s hard,” McCormick said of Wheeler’s repertoire. “We can hit hard.”

Valdez’s profile is vastly different. He attacked as he always does, with a devastating curveball and a hellacious sinker, weaving in and out of traffic to allow only one run in 6⅓ innings. The Phillies threatened to begin the sixth, placing the first two batters on base for the heart of their order. But Valdez struck out J.T. Realmuto on a high fastball then got Bryce Harper to bounce into an inning-ending double play. Of Valdez’s 19 outs, nine came via strikeout and nine came on the ground. Only five of the Phillies’ batted balls left the infield.

Through three starts, Valdez’s postseason ERA stands at 1.42.

“This guy has been as consistent as any pitcher that I’ve ever had throughout the course of the year, and he just continued to do the same thing during the playoffs,” Astros manager Dusty Baker said of Valdez, who set a record with 25 consecutive quality starts during the regular season. “He gets big outs. He makes big pitches.”

The Astros will play their next three games in what promises to be a raucous Citizens Bank Park in Philadelphia, needing at least one victory to bring the series back to Houston. They’ve essentially lost home-field advantage, but two glaring positives emerged from their time at home. One is that they combined for 10 runs against Wheeler and Aaron Nola, the Phillies’ fearsome pitching duo. The other is that Altuve might finally be turning the corner.

Altuve, an eight-time All-Star and three-time batting champion, began this postseason mired in a head-scratching 0 for 25 slump. But he followed with four hits in a 12-at-bat stretch heading into Saturday, and then he seemingly broke out. Altuve lined a double to left in the first, grounded a base hit up the middle in the fifth and lined a single to right — on a fastball near the height of his head — in the seventh.

He laughed to himself when he arrived at first base, as he should.

“Early in the playoffs, I was swinging at everything and then getting slowly better at swinging at my pitch,” Altuve said. “Yeah, I got a hit on a pitch almost above my head today. But it’s a hit, so it’s good.”