As bad as that was, a huge error and Addison Russell's game-ending RBI double really stung.
Washington wasted Jordan Zimmermann's solid start and lost 3-2 to the Chicago Cubs on Tuesday night on Russell's clutch swing in the ninth.
Bryant's towering drive in the eighth tied it at 2 and helped set the stage for the winning rally in the ninth.
Chris Coghlan had a one-out single against Matt Grace (2-1) before the Cubs caught a huge break when shortstop Ian Desmond threw wide to first while trying to turn a potential double play on Jonathan Herrera's grounder to second.
"(Coghlan) came in hard like you're supposed to do," Desmond said. "I thought I could still have a chance, but I hit the one spot in the fence where I wasn't supposed to, but it comes with the territory. You've got to take a chance once in a while. Unfortunately, this time, it didn't pay off."
The inning continued, and Russell lined a 1-0 pitch beyond center fielder Denard Span's reach for the rookie's third hit of the game.
"It wasn't a good pitch in that count," Grace said. "It was up in the zone and that's pretty much the gist of it."
Russell's hit made a winner of Hector Rondon (3-0), who worked a scoreless ninth. It also gave Chicago a major league-leading 13 one-run victories and sent the Nationals to their second loss in 10 games.
Zimmermann and Chicago's Kyle Hendricks each turned in strong outings, allowing one run over seven innings.
Dexter Fowler put the Cubs in front with a leadoff homer in the first. It stayed that way until Bryce Harper led off the seventh with his National League-leading 17th homer, driving the ball to about the third row in left field.
The Nationals went ahead when Span connected against Pedro Strop with two out in the eighth, belting a drive to right for his second homer in as many games. But Bryant went deep in the bottom half.
Bryant's seventh homer came on a full-count pitch from Aaron Barrett after he fell behind 0-2 in the count. The rookie also flied out twice to the warning track in center.
"Everyone just stood up to see how far it would go," Russell said. "When he hits balls, they go far. Us as a team, we're used to seeing it. But the whole world's seeing it. It's just a cool feeling. The world gets to see what he has to offer."
The long balls overshadowed strong starts by Hendricks and Zimmermann.
Hendricks, coming off his first career shutout last week at San Diego, gave up four hits. Zimmermann allowed six hits, but the NL East-leading Nationals lost for just the sixth time in 26 games.
Nationals: RF Jayson Werth (bruised left wrist) rejoined the team, but manager Matt Williams is not sure when he will be activated from the disabled list. Werth, batting .208, can't swing. ... RHP Doug Fister (right forearm tightness) is scheduled to begin throwing on Wednesday. ... INF Anthony Rendon (oblique, left knee) played three innings in a simulated game and is scheduled for five more on Wednesday. He is expected to take Thursday off and being a minor league rehabilitation assignment on Friday.
Cubs: Manager Joe Maddon said OF Chris Denorfia (strained left hamstring) is "not too far off," but would not put a timetable on his return. The same goes for RHP Neil Ramirez (right shoulder inflammation) and infielders Tommy La Stella (right rib cage inflammation) and Mike Olt (hairline fracture in right wrist).
Free-agent prizes will be on the mound when Cubs LHP Jon Lester (4-2, 3.56 ERA) and Nationals RHP Max Scherzer (5-3, 1.67 ERA) start the finale of the three-game set. Lester is 4-0 in five starts in May after going 0-2 in April. Scherzer, the 2013 AL Cy Young Award winner, has won four straight starts.