This time the Diamondbacks were the ones being beaten.
Adam LaRoche hit a game-winning solo home run with two outs in the 11th inning to help the Nationals beat the Diamondbacks 5-4 Monday night for their seventh straight win.
It was the third walk-off win in as many days for NL-East leading Washington, the first two coming against the Pirates.
''They don't come around very often that's for sure,'' Williams said, ''but (we) just keep fighting.which is a great trait to have.''
LaRoche sent a 3-1 pitch from Will Harris (0-3) off the wall in the back of the Nationals bullpen and was mobbed by his teammates at home plate.
''I got every bit of it, I did,'' LaRoche said. Just a crazy few days. I don't know how we've gotten these walk off situations the last few days, but we have and have been able to grind back.''
It was LaRoche's first career walk-off homer.
''Nice to get my first one, it took me long enough,'' the 34-year-old said.
Winning pitcher Craig Stammen (3-4) pitched out of a bases-loaded, no outs jam in the top of the inning.
''We missed our opportunity, me striking out instead of putting the ball in play,'' said Didi Gregorius, who made the second out against Stammen.
Arizona tied it 4-4 when David Peralta led off the ninth with a solo homer off Tyler Clippard.
Washington trailed 3-2 when Denard Span doubled with one-out in the eighth against Brad Ziegler and Anthony Rendon followed with a triple to tie it. Jayson Werth then scored Rendon with a sacrifice fly.
Miguel Montero had three hits for Arizona, and rookie Ender Inciarte extended his hitting streak to 18 games.
Arizona had taken the lead in the top of the eighth.
Jake Lamb drew a lead-off walk off Jordan Zimmermann, and Gregorius sent a 3-2 fastball into the Nationals bullpen for his fifth home run.
Wilson Ramos had given Washington a 2-1 lead with a two-run homer off Arizona starter Vidal Nuno in the seventh.
Nuno, winless in eight starts with the Diamondbacks, pitched well, allowing two runs and five hits over seven innings.
Zimmermann went seven-plus innings, allowing three runs on four hits. His three walks were a season-high.
He faced the minimum through four innings thanks to a pair of double plays.
In the fifth however, the first two Diamondbacks reached base via a walk and a single. Manager Kirk Gibson had No. 6 hitter Jordan Pacheco bunt the runners over, and Lamb's sacrifice fly made it 1-0.
Diamondbacks: SS Chris Owings, on this disabled list with a strained left shoulder, began a rehab assignment Sunday with the team's Arizona Rookie League affiliate, going 2 for 3.
Nationals: Werth (sore shoulder) was in the starting lineup for the first time since Aug. 10. . OF Nate McLouth, out since Aug. 2 with right shoulder inflammation, was scheduled to undergo an Arthrogram - an MRI procedure that involves dye being injected into the joint - on Monday to help determine the extent of his injury.
Diamondbacks: RH Chase Anderson (7-4, 3.16) is 2-0 with a 2.19 ERA in his last six starts.
Nationals: RH Stephen Strasburg (9-10, 2.53) pitches Tuesday at Nationals Park, where he's 7-2 with a 2.41 ERA this season.
Washington second baseman Asdrubal Cabrera was shaken up, but remained in the game after a third-inning collision at second base. On a sacrifice bunt attempt by Jordan Zimmermann, Cabrera slid into second and the side of his head slammed against the knee of Gregorius's, who was fielding the throw. Cabrera remained on the ground for several minutes as manager Matt Williams and the trainer came out to check on him.
Inciarte is tied with Jose Abreu of the White Sox for the second longest hitting streak this season by a rookie. Abreu had a 21-game streak as well. . Mark Trumbo (1 for 4 with a walk) has reached base safely in 17 straight games, and hit safely in 15 of 17, going 21 for 61 (.344).