Kyle Hendricks outpitched Stephen Strasburg, and the Chicago Cubs opened defense of their first World Series title in 108 years with the shutout game.
Kris Bryant and Anthony Rizzo produced RBI singles in the sixth inning for the first two hits off an otherwise-dominant Strasburg. Hendricks was even better, giving up only two singles in seven strong innings.
Rizzo added an RBI double off reliever Ryan Madson in the eighth. Carl Edwards Jr. threw a perfect inning and Wade Davis finished the two-hitter for a save.
Game 2 in the best-of-five series is Saturday, with Jon Lester set to start for Chicago against fellow left-hander Gio Gonzalez.
Strasburg didn't allow a hit until there were two outs in the sixth. Javier Baez reached on third baseman Anthony Rendon's error to start the inning and was sacrificed to second by Hendricks. One out later, Bryant drove in the first run with a single to right-center and went to second when Bryce Harper missed the cutoff man.
The next batter, Rizzo, singled to right in front of a diving Harper to make it 2-0.
With a heavy beard and a lot of sweat on a muggy, 77-degree night, Strasburg dialed up his fastball to 97 mph and occasionally used an unhittable changeup. To cheers of "Let's go, Strasburg!" from many in a sellout crowd of 43,898, he held the Cubs without a hit for 5 2/3 innings and wound up with 10 strikeouts, a playoff record for the Expos-Nationals franchise.
In only his second postseason appearance - remember the shutdown of 2012 and the arm injury of 2016? - the righty showed precisely the sort of power and poise that made him the No. 1 pick in baseball's amateur draft. Until, that is, the sixth inning. That's when everything changed in a matter of minutes.
Until then, the Cubs managed only one baserunner, and that was via a walk. But Baez led off with a bouncer that Rendon gloved, then bobbled while trying to transfer it to his throwing hand. It was Rendon's first error since July 22; he made only seven in 145 regular-season games.
After Hendricks' bunt moved Baez to second, 2016 NL MVP Bryant lined Strasburg's 60th pitch, a four-seam fastball, to right-center for the game's first run. Harper's throw missed the cutoff man, and Bryant took second. Two pitches later, on another fastball, Rizzo sent a sinking shot to right, where Harper came up just short trying to make a diving catch, and suddenly it was 2-0. As pitching coach Mike Maddux came out for a mound visit with Strasburg, Rizzo whooped it up at the bag, high-fiving first base coach Brandon Hyde.
Strasburg wound up allowing those two unearned runs in seven innings, with three hits and one walk.
Hendricks went about things differently - his best fastball is about 10 mph slower than Strasburg's - but was every bit as good. The slender righty from Dartmouth, who led the NL in ERA last season, did not give up a hit after the second inning. He walked three batters and struck out six.
In the Washington ninth, Ryan Zimmerman was called out when catcher Willson Contreras' throw hit the player in the back as he ran to first on a dropped third strike.
While the Cubs are no longer the "Lovable Losers" after last year's championship, the Nationals were the NL East champions for the fourth time in six seasons but have yet to win a playoff series.
Their undoing in the past has often been poor hitting and bad relief pitching, and it was the former that was most glaring this time.
Yes, Harper - wearing shoes with "Pray for Las Vegas" written on the side following the recent mass shooting in his hometown - did single in the first inning, but was 0 for 3 in his other at-bats as he tries to regain his timing after returning recently from a long injury layoff. Rendon, Zimmerman, Daniel Murphy, Trea Turner and Jayson Werth were a combined 0 for 17 with three walks.
Despite the rain, Wrigleyville was still filled with playoff fever. Fans said this year, like last year, is the Cubs' year.
"I'm hoping for a repeat. That would be great. That would be really cool for the city.
"We're so excited to have them back. Playing last year was pretty magical, so we'll see," said Cubs fan Carol Costakis.
But even though the game is in Washington, D.C. security around Wrigley will be tight.
Fans rooting for the Cubbies watched them by video board at the Park at Wrigley after passing through a security checkpoint. A spokesperson for the team said there were also bag searches.
Before the game police lined the streets and crowd control measures were put in place. Officers in the crowd were joined by private security.
"I've been waiting since last week to get out here. I've been waiting. I didn't have to think. I wasn't worried. It's great security around here," said James Lyons, Cubs fan.
The heightened concern over public safety and security comes in the wake of the Las Vegas mass shooting, which killed 58 and injured more than 500 concertgoers.
The Chicago Police Department plans to deploy more officers over the weekend to assist with the event, city officials said.
Despite the security challenge, Sports World Chicago owner Brad Rosen said he wasn't worried.
"We've been waiting all year, and we just can't wait for the playoffs to start again," Rosen said. "The energy in the neighborhood is exciting."
First pitch for Friday's game was thrown by House Majority Whip Steve Scalise.
Saturday's game begins at 4:38 p.m., also in Washington.
The series arrives at Wrigley for Monday's game, which begins at 3:08 p.m. or 4:38 p.m. if both ALDS series are complete. Tuesday's game starts at 3:08 p.m., also at Wrigley.
If Game Five is necessary, it will be held in Washington on Thursday at 5:38 p.m.
CUBS ANNOUNCE 2017 NLDS ROSTER
The Chicago Cubs announced their National League Division Series roster Friday morning.
Pitchers on the roster are Carl Edwards Jr., Kyle Hendricks, Brian Duensing, Jon Lester, Justin Wilson, Mike Montgomery, John Lackey, Pedro Strop, Jake Arrieta, Jose Quintana, and Wade Davis.
Infielders are Tommy La Stella, Ian Happ, Javier Baez, Kris Bryant, Ben Zobrist, Addison Russell, and Anthony Rizzo.
Outfielders are Albert Almora Jr., Kyle Schwarber, Jason Heyward, Leonys Martin, and Jon Jay.
Also on the roster are catchers Willson Contreras and Alex Avila.
Cubs: Lester makes the 20th postseason start of his career, which includes three World Series titles and an NLCS MVP award last year. He is 9-7 with a 2.63 ERA over his postseason career.
Nationals: Gonzalez goes in Game 2 instead of two-time Cy Young Award winner Max Scherzer, who is slated for Game 3 at Wrigley Field on Monday. Scherzer has been dealing with a sore right hamstring. It will be Gonzalez's first playoff start at home since Game 5 of the 2012 NLDS against St. Louis, when he was staked to a 6-0 lead in a game Washington lost 9-7.
The Associated Press contributed to this report.