Given zero wriggle room, Nationals reliever Ryan Mattheus had realistic expectations. Entering with the bases loaded, nobody out and the cleanup man coming to the plate in the seventh inning, it was all about not letting the game get out of hand.

ST. LOUIS (AP) — Given zero wriggle room, Nationals reliever Ryan Mattheus had realistic expectations. Entering with the bases loaded, nobody out and the cleanup man coming to the plate in the seventh inning, it was all about not letting the game get out of hand.

"I'm thinking minimize the damage," Mattheus said. "No big inning here."

He needed just two pitches to diffuse the crisis and keep it close for a deciding rally in Washington's 3-2 victory over the St. Louis Cardinals in a division series opener on Sunday. Allen Craig, who batted an NL-leading .400 with runners in scoring position, grounded into a force at the plate and Yadier Molina bounced into an easy double play.

"It was a big moment," said Mattheus, who gave a big fist pump before walking off the mound. "It gave us life. The guys said, 'Hey, we can win this ballgame."

Rookie pinch-hitter Tyler Moore's big moment came just a few minutes later. Moore, who had two of the Nationals' three pinch homers, looped a two-out, two-run single off Marc Rzepczynski for the go-ahead hit.

There are just four players with postseason experience on the roster, but the Nationals led the National League with 98 wins. It's a huge step for a franchise that hadn't even come close to making the postseason since moving from Montreal in 2005, and brought postseason baseball to the nation's capital for the first time since 1933.

Washington overcame a wild start by 21-game winner Gio Gonzalez, who matched his career worst with seven walks. Five pitchers combined on a three-hitter against the Cardinals, who made it to the best-of-five division series by beating the Braves in a one-game playoff.

Tyler Clippard skirted an error in the eighth and Drew Storen got the save with a 1-2-3 ninth against the top of the order.

"Being able to grind out a win in this place, that's huge," rookie center fielder Bryce Harper said. "Our bullpen came in and threw awesome."

The NL East champions go for a 2-0 series lead Monday when Jordan Zimmerman, whose 2.92 ERA ranked among the league leaders, faces Jaime Garcia, whose career 2.48 ERA is the best among major league starters at 7-year-old Busch Stadium.

"We just lost a game," said third baseman David Freese, the MVP of the NLCS and World Series last fall. "We're going to wake up tomorrow ready to go."

The Cardinals wasted a 10-strikeout gem by Adam Wainwright, failing to capitalize enough on Gonzalez's career high-tying seven walks and frustrating their towel-waving fans.

"He's the best non-knuckleballer in the league," Freese said of Gonzalez, in a nod to the Mets' R.A. Dickey. "He's nasty."

A standing room crowd of 47,078, among the largest at 7-year-old Busch Stadium, bundled up for a game that began in a 54-degree chill and featured kaleidoscope late-afternoon shadows that bedeviled hitters for several innings.

Rookie shortstop Pete Kozma misplayed Michael Morse's grounder for an error to open the eighth and set up the Nationals' go-ahead rally. Desmond followed with a single off Mitchell Boggs, putting runners at the corners.

Danny Espinosa sacrificed, putting runners at second and third with one out. Nationals manager Davey Johnson sent up Chad Tracy with two outs and switched to Moore after Cardinals manager Mike Matheny opted for Rzepczynski, his lone bullpen lefty.

Rzepczynski was happy with his pitch, but Moore poked it to right field and both runners scored easily.

Johnson doesn't usually play small ball but opted for the bunt because Espinosa struck out three times earlier against Wainwright.

"I'm kind of from the Earl Weaver school, just keep swinging," Johnson said. "Don't like to steal that much, either. I don't like to give up outs."

Wainwright became the first Cardinals pitcher to reach double digits in strikeouts in the postseason since Bob Gibson also fanned 10 to beat the Tigers in Game 4 of the 1968 World Series.

Wainwright was a 14-game winner coming off reconstructive elbow surgery that sidelined him all of 2011, with 10 of the wins coming at home. He's been a postseason ace with a microscopic 0.77 ERA and 32 strikeouts in 23 1-3 innings.

He also fanned Harper and Ryan Zimmerman twice each.

"My fastball command kind of left me at the end," Wainwright said. "For the most part I felt like I went out there and competed my tail off. Gave it everything I had."

Gonzalez allowed just one hit in five innings, Freese's full-count bouncer between third and short to start the fourth. But he had trouble finding catcher Kurt Suzuki's glove and keeping warm.

"I kept blowing in my hand, kept looking to do whatever I could to throw a strike," Gonzalez said.

The second inning was his shakiest, when he allowed the Cardinals to score twice and take the lead without a hit. Gonzalez walked four of the first five hitters, putting St. Louis in position to score one run on a wild pitch and a second on Jon Jay's bases-loaded sacrifice fly.

"The whole time I was just saying minimize the damage because things were spinning out of control," Gonzalez said. "I just wanted to match everything Wainwright did. I was trying to keep up with him."

Nationals right fielder Jayson Werth robbed Daniel Descalso of a two-run homer off with a leaping catch to keep it at 2-1 in the sixth. Descalso had a fielding gem of his own in the seventh, ranging far to his left to glove Harper's grounder and then throwing him out by a few steps.

NOTES: The Cardinals went 0 for 8 with runners in scoring position. ... Garcia was 4-2 with a 2.82 ERA in nine starts at home. The lefty has a 2.48 career ERA at Busch. ... Gonzalez also walked seven on June 11, 2011, when he was with Oakland against the White Sox. ... Kozma committed one error in 26 games after taking over as the regular SS in September for injured Rafael Furcal.