The game was tied at 1 in the ninth, and Werth -- leading off in the bottom of the inning -- battled Cards reliever Lance Lynn, hitting the 13th pitch of the at-bat over the left-field wall for the 14th postseason home run of his career, his first this postseason.
"He beat me. I've had success with him all series," Lynn said. "Everyone in the city knew what I was throwing there. Tip your cap to him. The guy can play, and he beat me. ... I was making good pitches, making my pitches. He won. That's part of the game. I would have loved for it to go the other way and for him to have rolled over that pitch. But sometimes, it doesn't work out in your favor. I was challenging him, and he was up for it."
Everything was a blur for Werth. He had to go back to the video room to see how everything went from the first pitch to the 13th pitch.
"I don't even remember it," Werth said. "It's almost like I blacked out, for sure. It was a Will Ferrell moment. I remember bits and pieces."
After he fouled off Lynn's 12th pitch, Werth looked at the scoreboard and couldn't believe he was at the plate that long.
"I looked at the scoreboard and I saw 12," Werth said. "I was like, 'Is that right?' I really had to study the board to make sure that was correct. I guess it didn't last much longer."
On the 13th pitch, Werth hit the game-winner. At first, he wasn't sure if the ball was high enough to go out of the park, but his emotions said it all when it went into the Cardinals' bullpen.
"Trent [Jewett], our first-base coach, he never comes and gives you a high five on homers," Werth said. "I've been on him for the last two years. I ask, 'Why don't you come give me a high five?' Davey Lopes, I had him for four years in Philly and he would always give me the high five. Trent finally gave me a high five on a home run. I knew then it was a special moment."
Jewett wasn't the only one who felt Werth's home run was a special moment. Manager Davey Johnson was pretty happy about the outcome.
"[Werth is] a remarkable guy. He can force a pitcher to throw a lot of pitches," Johnson said "That's the way that game should have ended -- Jayson Werth hitting a home run. He has not hit that many this year. What was it, a 13-pitch at-bat, something like that? It was unbelievable. Great effort on his part."
Werth has given 100 percent effort since he signed a seven-year, $126 million contract with the Nats after the 2010 season. In his first year in Washington, Werth had arguably his worst season as a regular, but that didn't stop him from changing the culture in the clubhouse and teaching the young players how to play the game the right way. In fact, teammate Bryce Harper calls him "The captain."
"Last year didn't go as well as he wanted, but what I think he did in the clubhouse from Day 1, he changed the culture," said closer Drew Storen, who allowed Werth's last walk-off homer prior to Thursday, on Sept. 9, 2010. "He has been a huge part of the team's success. [It's great] for him to finally get something like this ... and get the admiration that he deserves. He is one of the main reasons why we are here. I can't say enough good things about him. He's a great teammate and a great leader."
Right-hander Kyle Lohse started for St. Louis and was able to overcome his issues with the Nationals during the regular season, when he allowed nine earned runs in 11 2/3 innings.
It was a different story on Thursday, as Lohse allowed one run in seven innings. That run scored in the second inning, when Adam LaRoche hit a 3-2 pitch over the center-field wall for his second home run of the postseason.
After the home run, Lohse allowed one hit, a single to Ryan Zimmerman, in the next five innings.
Nats left-hander Ross Detwiler pitched on 11 days' rest, but unlike the rest of the starting rotation, he didn't have any problems with St. Louis, pitching six innings and allowing one unearned run, which came in the third inning.
Jon Jay hit a soft ground ball to shortstop Ian Desmond, who bobbled the ball for an error and put runners on first and third. Carlos Beltran then hit a sacrifice fly to Harper in center field, scoring Pete Kozma.
"It was fastball location," Detwiler said. "I think I mixed more pitches early on the game. The last few starts, I was fastball happy and really didn't get a feel for my offspeed pitches."
After Detwiler's exit, the Washington bullpen took over and dominated. Jordan Zimmermann made his first relief appearance as a big leaguer, striking out the side in the seventh.
Tyler Clippard took over in the eighth inning and also struck out three, around a walk.
Then came Storen, the winning pitcher, who struck two out of the four hitters he faced to keep the game tied, setting the stage for Werth.
"It was electric. It's been that way most of the year. But in both cases, the job [the relievers] did was they rose to the occasion," Johnson said. "All of them were throwing harder than I've seen them throw. ... They say I'm supposed to give a big speech before the game to get them all pumped up. No. These guys are pumped up. They don't need any motivation."
The Nationals now go to Game 5 with NL Cy Young Award candidate Gio Gonzalez on the mound.
"The score is 0-0. We have a tough game," Werth said. "This is what it's all about. This is why you work out all winter and why you start playing tee ball when you are 4. This is baseball, man. That's why you play."
Bill Ladson is a reporter for MLB.com and writes an MLBlog, All Nats All the time. He also could be found on Twitter @WashingNats.