(SportsNetwork.com) - Dallas Keuchel goes after his third straight win on Tuesday when the Houston Astros open a two-game series with the Washington Nationals at Nationals Park.

Keuchel has been one of the better pitchers in baseball this season, especially of late, as he is 6-1 with a 1.33 ERA over his last seven starts, allowing 37 hits and only seven walks in 54 1/3 innings.

The 26-year-old left-hander was terrific on Wednesday against Arizona, as he allowed a run and four hits in eight innings to run his record to 8-3, while lowering his ERA to 2.38.

Keuchel, who only had nine career wins entering this season, did not record a decision in his only other start versus the Nationals.

"It'll definitely be a good test," Keuchel said of his start versus the Nats. "It's just a quick two-game set, but at the same time, it's a good test to see where we're at and see where they are because we're playing pretty well, too. They have a great starting rotation. It will be key for me to come out and settle in early and get my thing going."

Houston has been playing well lately, but stumbled this weekend, as it dropped two of three to the Tampa Bay Rays, including a 4-3 setback in Sunday's rubber match at Minute Maid Park. Dexter Fowler and Matt Dominguez hit solo homers for the Astros, who lost for just the fourth time in their last 10.

Jerome Williams (1-3) was tagged in defeat for two runs on five hits over his two-inning relief stint.

Washington, meanwhile, limps into this series having dropped four in a row after a 5-2 loss to St. Louis on Sunday.

Jayson Werth and Adam LaRoche each knocked in a run for the Nationals, who saw starter Doug Fister (5-2) give up four runs on seven hits over six innings. Fister had won five consecutive starts.

"The sweep hurts," Fister admitted. "You always want to win a series. You never want to get swept."

Hoping to reverse their recent fortunes on Tuesday, the Nats will rely on righty Tanner Roark, who is 5-4 with a 2.92 ERA. Roark won his second straight start on Wednesday in San Francisco, as he gave up a pair of runs and seven hits in six innings.

Roark has never faced the Astros, who have lost six in a row and nine of their last 10 to the Nationals.