WASHINGTON (AP) -- Adam LaRoche hit a game-winning solo home run with two outs in the 11th inning to help the Washington Nationals beat the Arizona 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.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. Winning pitcher Craig Stammen (3-4) pitched out of a bases-loaded, no outs jam in the top of the inning.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, 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 Didi 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.