Danny Espinosa's RBI single during a two-run seventh inning proved to be the difference as the Washington Nationals escaped with a 4-3 win over the St. Louis Cardinals in the finale of a four-game series on Sunday.

Kurt Suzuki smashed a solo home run and added an RBI base hit, while Ian Desmond chipped in with a run-scoring single for the NL East-leading Nationals, who have won four of their last five games.

Espinosa's single made a winner of Ryan Mattheus (5-1), who tossed 1 1/3 innings of relief behind starter Stephen Strasburg. Tyler Clippard picked up his 29th save of the year with a perfect ninth.

Strasburg pitched six scoreless innings with nine strikeouts and one walk. He allowed just two hits in a no-decision.

He is now 3 2/3 innings away from his limit of 160. Once he reaches that number, he could be shut down by the club for the remainder of the regular season.

"It's huge," Strasburg said of taking 3-of-4 from the Cardinals. "We want to protect our park. When teams come in here, we want to make sure we play our caliber of baseball."

Lance Lynn (13-6) took the loss after surrendering two runs on four hits in the seventh inning. Daniel Descalso smacked a two-run home run and Tony Cruz added an RBI double for the defending World Series champs, who lost three of four in this series.

Michael Morse started the Washington rally in the seventh with a two-out single to left and Chad Tracy followed with a base hit. Pinch-runner Eury Perez then stole third and scored on a single up the middle by Desmond to make it 3-2. Espinosa then hit one back through the box to score Tracy for the two- run edge.

Cruz doubled off the wall in left-center field in the eighth to score David Freese, but Clippard went through Descalso, Skip Schumaker and Jon Jay with ease in the ninth to finish off the win.

After Allen Craig was thrown out at the plate by Bryce Harper to end the top of the fourth, the Nats took the lead in the home half when Suzuki got a sinker from St. Louis starter Jake Westbrook and smoked it over the left-field wall.

Washington extended its lead to 2-0 in the sixth. Desmond started the rally with a one-out single and moved into scoring position on a base hit to right field by Espinosa. Suzuki followed and came up clutch again, as he ripped a line drive back up the middle to score Desmond.

"He's only hitting eighth because they're lineup is so good," Westbrook said of facing Suzuki. "He's a really good hitter."

After managing just a pair of hits off Strasburg through six innings, the Cards scored twice against Sean Burnett to tie the game.

Freese and Cruz went down quietly to begin the frame, but Peter Kozma got things started with what seemed like an innocent base hit. Burnett then left a fastball up to Descalso, who smashed it over the right-field wall and into the bullpen.

Game Notes

Washington improved to 81-52 this season, surpassing its win total for all of 2011 ... Westbrook allowed two runs on nine hits with a walk and six strikeouts over 5 1/3 innings ... Nationals outfielder Jayson Werth was a late scratch from the starting lineup due to a hamstring problem. He was replaced in the leadoff spot by Roger Bernadina ... St. Louis went 1-for-6 with runners in scoring position and left seven on base.