The second-place Braves can make a move toward unseating Washington from that spot when the teams begin a three-game set on Friday night at Turner Field. Atlanta trails by 3 1/2 games after falling to the D-backs, 3-2, in its series finale against Arizona on Thursday night.
The Nationals have gone 4-1 against the Braves this season, including a three-game sweep in Atlanta in late May. That's one reason they hold the NL's best record and are in prime position to claim the franchise's first playoff spot since it moved from Montreal.
"It's all nice and good, but it's not October," manager Davey Johnson said before his team lost to the Rockies on Thursday. "I'll take it one day at a time. We haven't accomplished anything, but we're moving in the right direction."
Washington, which is 3-4 thus far on its 10-game road trip, will send Ross Detwiler to the mound to oppose Atlanta's Randall Delgado.
This will be the second start for Detwiler (4-3, 3.09 ERA) since the lefty was reinserted into the rotation for a struggling Chien-Ming Wang. On Saturday in Baltimore, he threw five shutout innings.
"I thought [Detwiler] was real aggressive going after them," Johnson said after the game. "He did attack the hitters, and I thought he was around the strike zone all the time. Sometimes he rushed a little bit, but by and large, he was in a good groove."
Delgado (4-8, 4.52) flashed his potential when he held the Orioles to two runs on three hits in eight innings on June 17. But in his next start, Saturday at Boston, he lasted only 1 1/3 innings, giving up four runs on six hits.
"When you bring a young starter along, there are going to be days where it's not going to look as good," manager Fredi Gonzalez said afterward. "Sometimes you're going to feel like the young man has turned the corner, and then he takes a step backwards. That's what we felt like happened today."
The 22-year-old righty does have a 3.59 ERA at Turner Field, compared with 5.73 on the road.
Nationals: Big bats come alive
Third baseman Ryan Zimmerman and outfielder Michael Morse, who both have battled injury and ineffectiveness this season, put together big series in Colorado. The question is whether they can continue that success after leaving Coors Field and the Rockies' beleaguered pitching staff.
Zimmerman had a .597 OPS when the four-game Colorado series began, then went 7-for-19 with two home runs and three doubles. Morse's OPS sat at .555 before he went 9-for-19 with a double and a homer.
The Nationals lead the Majors with 20 home runs from the first-base position this season. Adam LaRoche has 15 of those, with Tyler Moore adding three and Chad Tracy two.
Braves: Day off could be coming for Uggla
Braves manager Fredi Gonzalez seems to be leaning toward giving second baseman Dan Uggla a day off this weekend. Uggla hasn't missed a game this season, and has been slumping as of late, batting .108 (7-for-65) since June 6.
Uggla, however, has shrugged off his recent difficulties at the plate and remains confident in himself.
"It's no secret that I've had my struggles at the plate the last three weeks," Uggla said. "But I'm always going to fight, I'm always going to scratch, I'm always going to be in the game, I'm always going to do what I can do to help us win the game."
An 0-for-5 performance on Thursday night ended right fielder Jason Heyward's career-high 12-game hitting streak, during which he batted .455 (20-for-44) with four homers. He has hit safely in 20 of his last 25 contests and owns a .375 (30-for-81) average for the month, with 15 extra-base hits.
Detwiler has recorded a 3.52 ERA in his 10 starts, compared with a 1.35 mark in his six relief appearances. He gave up three runs in 4 1/3 innings to the Braves on May 25 in Atlanta.
Current Braves own a collective .945 OPS in 77 plate appearances against Detwiler, led by Martin Prado, who is 6-for-12 with three doubles and a triple. The only Washington player with experience against Delgado is starting pitcher Edwin Jackson, who is 1-for-2.