Having already surpassed their win total from last season, the NL East-leading Washington Nationals look to add another meaningful victory on Monday afternoon when they open a four-game series against the Chicago Cubs.

The Nationals have gone an outstanding 32-18 since the All-Star break and lead their division by 6 1/2 games over the Atlanta Braves. Washington's victory over the St. Louis Cardinals on Sunday gave it 81 wins on the season -- it won just 80 games last season -- to match the 2005 club's franchise-best total since relocating from Montreal.

A 4-3 victory over the Cards gave the Nationals a series win as they took 3- of-4 thanks to a two-run seventh inning that was highlighted by Danny Espinosa's RBI single.

Kurt Suzuki added a solo homer and RBI base hit and Ryan Mattheus picked up the win in relief of Stephen Strasburg, who hurled six scoreless innings and is slated to throw only two more starts this season due to an innings limit Washington has put him on.

"It's huge," Strasburg said of the series win. "We want to protect our park. When teams come in here, we want to make sure we play our caliber of baseball."

Outfielder Jayson Werth (hamstring) and first baseman Adam LaRoche (back) were held out of the starting lineup on Sunday, though LaRoche pinch-hit in the win. Both are expected to start this opener, which will see Ross Detwiler on the hill.

The Washington left-hander picked up his second victory in three starts on Wednesday at the Miami Marlins, yielding three runs on four hits and a walk over 5 2/3 innings. He improved to 8-6 with a 3.32 earned run average in 27 games (21 starts) this season.

Detwiler, 26, has split two career starts versus the Cubs with a 4.35 ERA.

Chicago tries to avoid a sixth loss in eight games on Monday and turns to starter Jeff Samardzija, who is coming off a solid outing that featured a tough-luck loss.

Facing the Milwaukee Brewers on Wednesday, the right-hander gave up all three runs in a 3-1 decision, but one was unearned. He also struck out 10 batters without a walk, falling to 8-12 with a 4.03 ERA in 26 games this season.

Following seven relief outings against Washington, the 27-year-old Samardzija made his first start versus the club on April 8 in his season debut, yielding three runs -- one earned -- and fanning eight without a walk in a victory.

The Cubs lost the final two contests of their three-game series against the San Francisco Giants, falling on Sunday 7-5 after reliever Carlos Marmol yielded two runs in the ninth inning.

Alfonso Soriano hit a three-run homer for Chicago, which lost two of three at home to Washington back on April 5-8.