Ryan Zimmerman's eighth inning single drove in the go-ahead run as the surging Washington Nationals capped a strong weekend with a 2-1 win over the Chicago Cubs on Sunday.

Nationals starter Jordan Zimmermann outdueled Jake Arrieta over six innings and left with a 1-0 lead. The Cubs tied it in the seventh on Starlin Castro's sacrifice fly against Drew Storen.

Denard Span's hustle turned a soft hit to right field off Pedro Strop (1-4) into a double leading off the eighth. Two outs later, the Cubs intentionally walked Adam LaRoche to bring up Zimmerman, who ripped a single to left that scored Span.

Tyler Clippard (6-2) pitched the eighth inning, and Rafael Soriano earned his 21st save for the Nationals, who have won seven of eight.

Washington took two of three games in the series, including 13-0 on Saturday to break Chicago's four-game winning streak.

Zimmermann allowed seven hits with one walk and struck out five. He has allowed two earned runs or fewer in seven straight starts. The right-hander is 3-2 with a 1.26 ERA in that span.

The Cubs had at least one hit in each of the first six innings, but couldn't generate a clutch one versus Zimmermann. Chicago left 12 runners on base and went 1 for 9 with runners in scoring position.

Following this weekend's blockbuster trade that sent starters Jeff Samardzija and Jason Hammel to the Oakland A's, Arrieta inherited the No. 1 role in the Cubs rotation. He has pitched to that level lately.

The righty won his four previous starts and flirted with no-hitters in his last two. Arrieta carried a perfect game into the seventh inning on June 24 against Cincinnati and went 7 2-3 innings without allowing a hit at Boston on June 30.

Washington ended such hopes immediately as leadoff hitter Span hit a fly ball that sailed over the outfielders for a double. Span moved to third base on Anthony Rendon's grounder to second and scored on Jayson Werth's groundout for a 1-0 lead.

Arrieta allowed four hits and one run over six innings with three walks and five strikeouts. He gave up two singles to open the fifth, but escaped the jam when Zimmermann struck out while attempting to bunt the runners over.

Storen entered having allowed only three earned runs this season and only one in 17 appearances since May 17.

The Cubs threatened in the eighth, putting runners at second and third with one out against Clippard, but didn't score. Pinch-hitter Wellington Castillo struck out looking, and Ryan Sweeney grounded out.

Justin Ruggiano, Anthony Rizzo, and John Baker all had two hits for the Cubs.