WASHINGTON — Joyous, bouncing teammates waiting to greet him at home, the red-clad crowd raucous as can be, Jayson Werth yanked off his red batting helmet with two hands and thrust it a dozen or more feet overhead.

A little less than two years ago, the Washington Nationals showered Werth with millions, persuading him to come show them how to win. On Thursday night, with one swing of his black bat, Werth delivered a game-ending homer to extend his club's surprising season and wipe away whatever disappointments marred his days in D.C.

Werth led off the bottom of the ninth inning with a 13-pitch at-bat against reliever Lance Lynn that ended with the ball landing beyond the wall in left field, giving the Nationals a tense 2-1 victory over the defending World Series champion St. Louis Cardinals and forcing a deciding Game 5 in their NL division series.

"That's the way that game should have ended: Jayson Werth hitting a home run," Nationals manager Davey Johnson said. "He has not hit that many this year. ... Unbelievable. Great effort on his part."

The best-of-five series will end Friday night in Washington, with the winner advancing to face the San Francisco Giants in the NL championship series. The starters will provide a rematch of Game 1, which Washington won, with Gio Gonzalez on the mound for the NL East champion Nationals, and Adam Wainwright for the wild-card Cardinals.

"It's what you play all season for, and what you work out all winter for, and what you get to spring training early for," Werth said. "We have a chance tomorrow to take that next step. I know my teammates will be ready. And the city will, too."

The homer was Werth's first of the series, the 14th of his postseason career. He won the 2008 World Series and a string of division titles with the Philadelphia Phillies , then moved to Washington before last season as a free agent on a $126 million, seven-year contract that stunned much of baseball.

He managed to hit only five homers and 31 RBIs in 2012, missing 75 games because of a broken left wrist. Last year, his first in Washington, Werth hit only .232 with 58 RBIs, and there was grumbling about his worth.

That vanished at dusk Thursday, when Werth circled the bases, raising his right index finger in a "No. 1" gesture, while the announced attendance of 44,392 roared, and the other Nationals raced out of their dugout to greet him.

"I'm just happy that these fans got to see it, because obviously he had a rough year last year, and he got hurt this year, and I don't think the fans realize how good of a player Jason is," Nationals third baseman Ryan Zimmerman said. "For him to have a moment like this in front of the home fans, and in front of this atmosphere, I couldn't be happier for him. He deserves it."

Werth's arrival certainly coincided with a quick turnaround: The Nationals lost 100 games in 2008 and 2009, but led the majors with 98 wins this year.

"When I signed here, my first day here, I went to a Capitals game, a hockey game, (and) the place was packed. Somebody said, `Just a few short years ago, this place was empty.' So I knew that a winning ballclub would bring the fans," Werth said, "and here we are, two years later, and they're showing up and it's awesome."

Werth's shot provided a sudden end to a classic postseason contest filled with tremendous pitching. Each team managed only three hits.

Lynn, usually a starter for St. Louis but a reliever in these playoffs, was making his third appearance of this series.

"Heater. He beat me," Lynn said, then paused before continuing. "I've had success this series with him, and, you know, everyone in the stadium knew what I was throwing there."

Especially Werth.

"It was just a matter of time," Lynn added. "I was challenging him, and he was up for it."

The righty was the Cardinals' third pitcher - facing only one batter - and manager Mike Matheny was asked afterward why he didn't use closer Jason Motte .

"If we were at home, it would have been a very easy decision to bring in Motte," Matheny said, explaining that if he used up his closer and St. Louis went ahead later in the game, a reliever not used to getting a save would have needed to try.

"Had a lot of confidence in Lance. He came in throwing the ball well," Matheny added. "Werth just put together a very good at-bat."

Cardinals batters decidedly did not down the stretch. They made eight consecutive outs via strikeouts against three Nationals pitchers - Jordan Zimmermann , Tyler Clippard and Drew Storen , who threw the top of the ninth and got the win. Zimmermann was making the first relief appearance of his career.

"All of them were throwing harder than I've seen them throw," Johnson said.

Storen walked No. 8 hitter Pete Kozma with two outs, before getting pinch hitter Matt Carpenter out on a twisting, stumbling overhead catch by shortstop Ian Desmond , who wound up sliding on his belly in short left field. When Desmond rose, he threw the ball into the stands and yelled.

Moments later, Werth had all the towel-twirling spectators yelling, too, thanks to the way he turned on a 96 mph fastball. For much of the game, the hometown fans were rather quiet, perhaps dreading a sooner-than-expected end to their team's better-than-expected year.

Starters Kyle Lohse , who won the wild-card playoff game for St. Louis against Atlanta last week, and Ross Detwiler were both superb. Lohse lasted seven innings, allowing one run and two hits. Detwiler went six, with one unearned run and three hits all he conceded, and called Werth's homer, "One of the best moments of my life."

Lohse was replaced by Mitchell Boggs , who struck out pinch hitter Chad Tracy with a man on to end the eighth, before giving way to Lynn.

While nearly to a man - except, naturally, for Werth - the young Nationals are new to this sort of thing, the Cardinals have quite the postseason pedigree: Over the past two years, St. Louis is 5-0 in games where it faces elimination, including must-have victories in Games 6 and 7 of the 2011 World Series against the Texas Rangers .

"We got a lot of experience, a lot of confidence built. Just going to the World Series and winning the World Series, having to play a Game 7 and come out on top - you're seeing a lot of us use that experience so far in this postseason," St. Louis first baseman Allen Craig said.

Washington entered Game 4 with all sorts of problems at the plate in the series: 3 for 24 with runners in scoring position, 30 men left on base, a total of only seven runs. Despite those struggles, Johnson didn't make any changes at all to his lineup.

As it turned out, the Nationals didn't have an at-bat with anyone in scoring position all game. Both runs came on solo shots.

Cleanup hitter Adam LaRoche put Washington ahead 1-0 in the second, and the Cardinals tied it in the next inning without a hit. Detwiler walked Kozma - a rookie Johnson referred to as "Cosmos" before the game - and after a sacrifice bunt, Jon Jay reached on an error when Desmond booted a grounder. Carlos Beltran 's sac fly scored Kozma.

No more scoring until the ninth, when Werth ended things.

A night earlier, Werth watched on TV as Raul Ibanez - his former Phillies teammate, now with the Yankees - pinch-hit for Alex Rodriguez in the bottom of the ninth and homered to tie an ALDS game against the Orioles, then went deep again in the 12th to win it. He traded texts with his buddy Ibanez.

Werth also tuned in to see Oakland rally to beat Detroit on Wednesday after trailing entering the ninth.

"Baseball, this time of year, is the best time for sports. I love October baseball," Werth said. "Here we are a day later, and I got an opportunity and came through."

Which means Werth - and the Nationals - get to keep playing.