A mostly empty Target Field in late September 2020 is a long way from a packed Dodger Stadium in early November 2017. A lot has happened to the Astros since they won their only World Series with a Game 7 triumph in Los Angeles three years ago, when starter Charlie Morton played the role of hero by throwing four innings of one-run ball in relief.

That blueprint, even under a different regime, still proved to be a reliable one for the Astros in Game 1 of the American League Wild Card Series on Tuesday afternoon. Lefty Framber Valdez -- perhaps their best starter -- threw five scoreless innings in relief and saw his team take advantage of a ninth-inning Twins error to rally for three runs in an improbable 4-1 win.

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“It’s incredible for me,” Valdez said. “It means a lot for me and the team for them to show me that kind of confidence in me to let me demonstrate the pitcher I am and always have been. And it’s been really huge for me to get to this point in the season. … I think this is going to be a great playoffs, both for me and the team.”

The Astros, who made the postseason with a 29-31 record, can now advance to the AL Division Series with a win in Game 2 at noon CT Wednesday over the Twins, who have lost a record 17 consecutive postseason games.

Valdez became the first relief pitcher to throw five scoreless innings in a playoff game since Madison Bumgarner in Game 7 of the 2014 World Series.

“We needed that kind of performance today,” said Astros second baseman Jose Altuve, who drew a bases-loaded walk to force in the go-ahead run in the ninth inning after a two-out error by shortstop Jorge Polanco. “It’s been like that all season long. That’s the kind of pitcher he is, and we’re happy for him.”

Altuve's walk was the first go-ahead walk in the ninth inning in postseason history.

Astros manager Dusty Baker said the plan all along was for Valdez to piggyback starter Zack Greinke, who they expected to pitch five innings. After four wobbly innings in which Greinke threw 79 pitches (46 strikes) and escaped a bases-loaded jam in the first, Baker turned to Valdez in the fifth. It was a terrific move.

Valdez walked the first two hitters, but then he retired the next 13 batters before giving up consecutive one-out singles in the ninth. Baker left him in, and he got Willians Astudillo to ground into a game-ending double play. Valdez threw 36 sinkers and 30 curveballs, getting seven swings and misses on a curve that’s among the most effective in baseball.

“We thought we got all we were going to get out of Greinke, because he was struggling a little bit,” Baker said. “He was good, but not as good as Greinke could be. We decided at that time to give him a different look. … Framber was awesome. He was outstanding. Boy, that was a good game to manage, play, watch.”

Valdez showed the strides he had made as a pitcher this year when he came in from the bullpen Aug. 2 and didn’t allow an earned run in 6 1/3 against the Angels in Anaheim. With injuries piling up, he was slotted into the rotation. Valdez went 5-2 with a 3.75 ERA in his next nine starts, and he led the club in innings pitched. In his first playoff game, he was composed and unfazed.

“I knew what the plan was coming in, and that’s why I was prepared and I was ready to go,” Valdez said. “I started getting ready around the third or fourth inning with the pitch count Greinke was at. I was prepared to come in and be successful as a reliever, and that’s what I did today.”

The emergence of Valdez into an effective starting pitcher has been one of the biggest bright spots of the season for the Astros. Valdez battled control problems the two previous seasons, but he put things all together this year with the help of the maturity that came from being a parent and working with a psychologist in the offseason.

“We weren’t exactly expecting their lefty to go out there and throw all of those innings,” Twins manager Rocco Baldelli said. “Very effective. He threw the ball very well. He was effective against all of our hitters … and once he settled in and found the strike zone, he made our lives difficult.”