Gio Gonzalez, just like most of his Washington Nationals teammates, hung on every pitch of Jayson Werth’s heroic at-bat in the bottom of the ninth from top of the dugout on Thursday. If he could have, Gonzalez said, he would have been higher than the top bench. The man who would be entrusted with winning Game 5 of the National League Division Series against the St. Louis Cardinals watched as Werth gave him the opportunity to do so with a walk-off home run to win Game 4.

“You have to watch it,” Gonzalez said. “You can’t miss that.”

Now the Nationals turn to Gonzalez, 27, the bubbly left-handed starter whom Washington shipped away four of its best prospects to the Oakland Athletics to acquire this winter. They turn to one of the major leagues’ best pitchers, a two-time all-star from Hialeah, Fla., who posted the best season of his career and vaulted himself among the top candidates for the NL Cy Young Award. Behind him, the Nationals feel they can breathe easy.

“We’ve got the guy we want on the mound for us in Gio,” General Manager Mike Rizzo said. “He’s our Cy Young guy.”

Overlooked in all the talk of what the Nationals lost when they shut down Stephen Strasburg in September was the performance of Gonzalez. Not only did he win 21 games, the most in baseball this season, the Nationals won more games with him on the mound than any other starter on the staff.

In games that Gonzalez started, the Nationals were 24-8, the most wins of any starting pitcher in the majors. Nearly 70 percent of the time Gonzalez took the mound this season, he gave the Nationals at least six innings and allowed three runs or less. He finished among the leaders in many of the major pitching categories: ninth-best earned run average, tops in lowest on-base plus slugging percentage against, second in hits allowed per nine innings, third-best strikeout rate, and more.

“Gio has been one of the best, if not the best, pitcher in the game this whole season,” reliever Tyler Clippard said. “He has really hit his stride in his career as far as he knows what he is capable of. For him to come back home, to pitch in front of this crowd in a big game like this, I think he relishes in those moments.”

In Game 1 of the series against the Cardinals on Sunday, Gonzalez struggled. He was affected by the chillier weather in St. Louis, the magnitude of the situation and a nine-day layoff in between starts. He was eager to get his second chance, this time on his regular five days’ rest, at home and with the experience of facing the Cardinals fresh in his mind. At Nationals Park this season, Gonzalez’s ERA is 2.38, nearly a run less than on the road.

“It was my first postseason game, no excuses, but the way I see it is playing in someone else’s house, pretty rowdy,” he said. “It’s pretty exciting. You catch yourself at the moment, take a step back and take a deep breath and try to find it again.”

Gonzalez’s command was shakier Sunday than it had been all season: He issued a season-high seven walks. But amazingly, in 110 pitches, he allowed only one hit and two runs. He knows he needs to pick his spots against the hot-hitting Cardinals.

“I kept my team in the game as long as possible,” he said. “I gave them five good innings and I gave them two earned runs. All said and done, with all that damage, you look at it for what it was, kept the team in the game.”

“He was disappointed about his first start,” third baseman Ryan Zimmerman said. “I don’t think he felt that he threw the way he was capable of. Gio’s an emotional guy — in a good way. That’s what makes him so good. He lives and dies with every pitch. . . . I think for him to get a second chance to try to redeem himself in front of this crowd at home, these pitchers, these guys have been unbelievable all year. They’ve really kept this team afloat.”

As reporters streamed into the clubhouse following the win, Gonzalez was pulling on a black jacket. Most of his teammates were still in the room, lingering and reveling in the moment. He enjoyed the electric moment with them on the field, but now he was off to rest, the biggest moment of his career awaiting him when he would climb onto the mound at Nationals Park shortly after 8:30 p.m.

“He’s our ace,” shortstop Ian Desmond said. “He’s going to bring it.”