The red-clad fans flowed into Nationals Park from Half Street early Wednesday afternoon, basking in bright sun and crisp, fall air. Four F-16s screeched overhead. Frank Robinson, the Washington Nationals’ first manager, threw out the first pitch and waved to an adoring, roaring crowd. The firsts unrolled one by one, pulsing through the stadium like an electric current, until the game unfolded and the home team still had not scored the first postseason run on Washington soil since Game 5 of the 1933 World Series.

Over nine emphatic innings, the stadium’s rabid, towel-waving joy devolved into cold, stark dread. The Nationals gave this city seven months of giddy thrills and spent 145 days in first place. After the St. Louis Cardinals throttled them, 8-0, in Game 3 of this National League Division Series before a record crowd, the Nationals who made Washington love baseball again may have only one game left.

“Don’t jump off a bridge,” General Manager Mike Rizzo said. “We’ve won two in a row before.”

Edwin Jackson’s rocky start, the Nationals’ sputtering offense and Chris Carpenter’s big-game chops pushed the Nationals to the brink, down 2-1 in the series and fighting an opponent that has dominated them over the past two weeks. Since the final weekend of the regular season, the Cardinals have beaten the Nationals four times in six games while outscoring them, 48-19.

The Nationals still maintained their resolve. Their clubhouse sat silent for five minutes, the TVs turned off, the room empty except for a pack of reporters. Right fielder Jayson Werth walked across the room, sat in his chair, cleared his throat and told the collection of cameras and notebooks: “We’ve been a really good team all year. We’ve got one game to play tomorrow — one game to win.”

“We are not out of this by a long shot,” Manager Davey Johnson said. “Keep us in the ballgame tomorrow, get a few key hits, we’re right back in it. Shoot, I’ve had my back to worse walls than this.”

Jackson allowed four runs in his first two innings, the fatal blow a three-run home run by rookie shortstop Pete Kozma, the Cardinals’ No. 8 hitter. Carpenter made only his fourth start this year because of a nerve issue in his neck, and he shut down the Nationals by dodging trouble.

The Nationals gave their crowd rallies to cheer, and then turned them into desperate deflation. They pushed runners to either second or third base in five of the first six innings. They went 0 for 8 with runners in scoring position and stranded 11 men on base. If not for shortstop Ian Desmond’s 3-for-4 performance, the series would seem even more lopsided than it already is.

“They’ve got some momentum, no question,” first baseman Adam LaRoche said. “They’re feeling really good right now, all aspects of their game. They’ve got that going for them. But today means nothing when we come out tomorrow.”

The latest drubbing left the Nationals’ season in the hands of Ross Detwiler , the 26-year-old left-hander who grew up rooting for the Cardinals and, essentially, replaced Stephen Strasburg in the postseason rotation. Detwiler, who allowed the Cardinals seven runs in 21 / 3 innings in his final regular season start, will oppose Kyle Lohse, the right-handed ace who went 16-3 this season.

“There can be points in the postseason that can stun you, I think, for a little bit,” Werth said. “I think we’ve been through enough here in these three games to get past that. We’re in a good spot. We got Det going tomorrow, and then Gio [Gonzalez] going Game 5. You got to win tomorrow to get that matchup in Game 5. But I like our chances.”

Before the Nationals clattered and popped, the anticipation for the team’s first major league home playoff game sizzled. As the teams lined up after pregame introductions, the crowd bellowed a “Let’s Go Nats!” chant. Bunting hung from the facing of the upper deck. As Carpenter warmed up in the bullpen, he thought the crowd was “amazing.” The place wanted to burst.

“Second to none,” said Desmond, who wears 20 in tribute to Robinson and caught his first pitch. “You could tell they hadn’t had a playoff game here in a while.”

The energy rose as Jackson retired the first two hitters of the game. But then Matt Holliday lined a two-out single to left, and Allen Craig roped an RBI double into the left corner. Jackson posted a 6.97 ERA in the first inning during the regular season, and so limiting the Cardinals to only one run felt almost like a win.

Then the second inning began, and the Cardinals plastered Jackson’s fastball. David Freese doubled and Daniel Descalso singled to put runners on the corners. Looking for a quick two outs, Jackson tried to throw Kozma an outside fastball. But he missed so far inside that catcher Kurt Suzuki skidded across the dirt on one knee just to position himself to catch it. Kozma rocketed the 94-mph fastball into the left field seats.

“If he is being aggressive and trying to turn and burn, it was the perfect pitch for him,” Jackson said.

Cardinals players emerged from their dugout, fists in the air. As Kozma jogged around the bases to put the Cardinals ahead, 4-0, a fan spewed back the home run ball. Carpenter, the opposing pitcher, followed with a single to right. Boos oozed from the 45,071-strong crowd that, minutes earlier, had waved towels and hollered in feverish hope.

The Nationals only fed their crowd more disappointment. In the fifth, the Nationals wasted their best chance to get back into the game. Still trailing, 4-0, the Nationals loaded the bases against Carpenter with a two-out single by Ryan Zimmerman and a tough walk by LaRoche.

Up came Michael Morse, in perhaps the most important spot of the Nationals’ season. Carpenter started him with two outside curveballs in the dirt. Morse could not check his swing at the first, and he barely did on the second. On the 1-1 pitch, Morse flared a 92-mph cutter to right field, an easy out for Carlos Beltran. All three runners skulked off the basepaths.

The Nationals would not threaten again. Afterward, they offered self-reminders that they won 98 games, that they are the top seed. “Over a 162-game season, we were the best team in baseball,” Werth said. “I still feel that way.”

“We got to realize we won Game 1 also,” reliever Craig Stammen. “They’ve kicked our butt two days in a row. But whether you lose 1-0 or 8-0, it counts as the same.”

By the latter innings, fans streamed of out the center field gates and back on to Half Street. They could not bear to watch the end of what they had waited 79 years for. Hours earlier, they had entered the park expecting so much. Now, as they formed a quiet sea of red, they could only hope the baseball season in Washington would last more than one more day.

“It’s frustrating, but in the same sense we know having the best record in the regular season doesn’t get us anything in the playoffs,” Zimmerman said. “There’s no panic in here. Would we like to up 2-1 instead of down 1-2? Of course. It’s not that way. We got to go out and win tomorrow.”