Already with a comfortable lead atop the National League East, the Nationals are in position to play for homefield advantage in October.
But the red-hot Phillies come to town Friday hoping to play spoiler. Philadelphia has won 10 of its past 15, including a series victory against the Wild Card-chasing Braves in Atlanta earlier this week.
Washington will turn to ace Stephen Strasburg, who had an up-and-down August. He allowed one earned run or fewer in four of his starts last month, while surrendering a combined 12 earned runs in the other two.
His last turn, during which he gave up one earned run in 7 2/3 innings against the Mariners on Saturday, was one of the good ones.
"This was the best that we have seen from him all year," Nationals manager Matt Williams said in Seattle. "He was really commanding his fastball that was 96 or 97 miles an hour, and the changeup off of it. He threw the changeup when he wanted to for strikes. He was really good tonight."
Opposite Strasburg will be Jerome Williams, who is competing to make a case to crack the Phillies' rotation next year. After posting a 6.71 ERA in 57 2/3 innings with the Rangers and the Astros, Williams has enjoyed pitching in the NL.
He is 3-0 with a 2.03 ERA through four starts in a Phillies uniform. On Saturday, Williams limited the Mets to two runs on four hits in 6 1/3 innings. Following that outing, Williams said this is the best he's felt since his rookie season in 2003.
"That's a long time ago," Williams said. "That's how I felt those first two years with San Francisco. I was really in a good groove. Then after that, I kind of lost myself. I lost a sense of pitching with what I had. I wanted to be other people. That was a downfall. Now I'm back to where I need to be as myself."
Nationals: Putting up power
Since going nine games without a homer from July 23 to Aug. 1, the Nats lead all NL teams with 48 homers since the beginning of August.
Adam LaRoche and Asdrubal Cabrera added to that total Wednesday, as both notched home runs in Washington's 14-inning, 8-5 win over the Dodgers. The Orioles, who have yet to play on Wednesday, lead the Majors with 50 in that span.
Ian Desmond, who leads Washington with 22 homers this season, has accounted for five of those home runs.
Phillies: Series-ly good
By taking two of three in Atlanta this week, Philadelphia has won four of its past five series. Each victory has come against a winning team as the Phillies have taken down the Mariners, Cardinals, Nationals and Braves.
Philadelphia finished August at 14-13, its first winning month since September 2012, and the Phillies have opened September with a 2-1 record.
• The Phillies have won six of their past nine games against NL East foes.
• Strasburg leads the NL with 210 strikeouts.
Joe Morgan is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.