HOUSTON -- Throughout his career, Stephen Strasburg excelled during the postseason -- but never quite like this. The right-hander ended his start Wednesday with perhaps two of the biggest outs of his career as the Nationals took a commanding two games to none World Series lead with a 12-3 win over the Astros at Minute Maid Park.

“He’s become a premier pitcher, a big-game pitcher,” said Nats manager Dave Martinez. “He doesn’t get rattled. He knows what he needs to do. He stays in the moment, which is huge for him. He doesn’t get overly excited when things happen. And he loves the big game. He really does.”

It doesn’t get much bigger than Game 2 of the World Series. And there was no bigger sequence than in the sixth inning with the game tied at 2 and the momentum in the balance.

As a serious threat mounted for the Astros in the sixth, the sold-out crowd at Minute Maid Park was looking for a reason to erupt. Houston had two on with one out, representing its best scoring chance since the first inning.

Yuli Gurriel got the inning started with a one-out double off Strasburg, which was then followed by an intentional walk to Yordan Alvarez after the right-hander fell behind 2-0 in the count. After the walk, the Astros’ win probability stood at 62.8 percent, according to FanGraphs.

As Strasburg hit the 100-pitch mark in the at-bat against Alvarez, he knew the end of his outing was near. He didn’t have many pitches left to work with, but the righty knew the last few pitches of his outing needed to be some of his best.

Strasburg delivered, and he did it thanks to his biggest weapon.

• Shock the world? Nope, Nats saw this coming

Throughout the year, secondary pitches have been key for Strasburg, especially his changeup. Strasburg began the night having allowed just four hits in 42 postseason at-bats against his curveball and changeup. His changeup in particular has proven to be one of the best in baseball. Opposing batters hit .140 off of it during the regular season, which was the third-lowest batting average against a changeup among Major League starters with at least 50 at-bats.

But on Wednesday, the Astros recorded five of the seven hits off Strasburg’s secondary pitches, and they were 3-for-8 on the changeup, including Alex Bregman's two-run home run in the first inning. It was the first time since Aug. 25 against the Cubs that Strasburg allowed three hits in a game on the changeup.

Still, Strasburg relied on his strength to escape the sixth-inning jam. He used a 3-2, 86 mph changeup to get Carlos Correa to pop up to second base for the second out of the inning. Then Strasburg turned to a 3-2, 82 mph curveball that struck out Kyle Tucker to end the inning.

“It was a big pitch for [Strasburg],” said Nationals catcher Kurt Suzuki. “He’s got so many weapons to get you out with. He’s got command. He can really spin the ball. You never really know what pitch is coming, because he can throw any pitch up at any time.”

Strasburg added: “I didn’t execute some pitches in that at-bat [against Tucker] early on and was able to get back into the count. I knew it was just one pitch and just had to trust it, commit to it, and I made the pitch.”

The escape with the game still tied allowed the Nats’ offense to get going. Suzuki homered off Justin Verlander to start the seventh, and the floodgates opened as Washington scored 10 runs over the last three innings in the Game 2 win.

• This inning gave the Nats control of World Series

“The thing about [Strasburg] is he’s really grown in that way where he doesn’t let things like that bother him,” Suzuki said. “He just moves on to the next pitch, gets the next out, moves on. He gave us five shutout [innings] after [the home run] and gave us a chance to win the ballgame. And it was great.”

• Suzuki: 'I've waited 13 seasons for this moment'

Strasburg’s career postseason ERA stands at 1.34 after Wednesday’s start. He improved to 4-0 this postseason and added another chapter to his playoff resume. The Nationals are now two wins away from hoisting the World Series trophy.

“I love playing this game and I’m going to play as long as I can,” Strasburg said. “Hopefully there are championships, but you really just have to focus on what you can control and leave it all out on the field.”