The Washington Nationals have won six straight series since they last faced the Philadelphia Phillies and extended their lead atop the NL East by four games.
The Phillies have made their own climb in the standings, but the reigning five-time division champs are still well out of the playoff race.
The Nats look to further their postseason hopes on Friday and prevent the Phils from picking up any momentum in the first of three straight contests between the clubs.
Washington has won five of nine versus Philadelphia this season, but lost two of three in the most recent meeting from July 31-Aug. 2 in D.C. The Nats left that set with a 2 1/2-game edge over the Atlanta Braves for first place, but have won 15 of 20 since to push that advantage to 6 1/2 games.
Philadelphia, meanwhile, was last in the standings following the Washington series and though it has fallen 19 1/2 games behind the Nats, the Phils hold sole possession of third place in the NL East for the first time since April 12. They are still 10 1/2 games back of a wild card position.
The Nationals recently took two of three from the Braves, failing to secure a sweep and a fourth straight win overall by dropping Wednesday's finale 5-1.
"We try to take two of three every time we play," Nationals third baseman Ryan Zimmerman said. "It was a good job this series, but we have to put it behind us and go to the next."
Edwin Jackson will need to forget his past against the Phillies, who he tries to beat for the first time in his career tonight. The right-hander is 0-3 in three meetings with a 5.60 earned run average, with two of those setbacks coming this year.
Jackson picked up a win over the Arizona Diamondbacks on Aug. 11 even though he allowed five runs over 5 2/3 frames. He then had the script flipped on him Saturday versus the New York Mets, yielding two runs over seven innings and striking out 11, but suffering a 2-0 setback. Both runs came on a homer in the seventh frame.
The 28-year-old sits 7-8 with a 3.69 ERA this season in 23 starts.
The Phillies earned a split of their four-game series with the Cincinnati Reds on Thursday, rallying for a 4-3 victory in 11 innings.
Philadelphia nearly wasted another opportunity to win the game after Domonic Brown grounded into a force out at the plate with the bases loaded in the 11th, but John Mayberry came through with a bouncing single that plated a run and ended the contest.
"I was trying to get something to the outfield. That was my approach," Mayberry said. "I didn't execute it exactly as planned, but I snuck one through there."
Philadelphia tries to make it back-to-back wins on Friday behind Kyle Kendrick, who has thrown two scoreless outings since getting hit for six runs over 3 1/3 frames in a start versus the Braves on Aug. 8.
Kendrick, who turns 28 on Sunday, has beaten the Miami Marlins and Milwaukee Brewers since, scattering eight hits and a walk over 15 innings while striking out 13. He fanned a career high-tying seven batters in an 8-0 win over the Brewers on Sunday.
"He did a good job. He got (Milwaukee outfielder Ryan) Braun out and he gets a medal for that," said Phillies manager Charlie Manuel of Kendrick. "That's the most pitches he's had this year. He's more confident when he's aggressive."
The right-hander is 6-9 with a 4.20 ERA in 29 games this season, including 17 starts.
Kendrick is 2-4 in his career against Washington with a 4.93 ERA in 16 games, all but two of those starts. Two of his three outings against the club this season have been starts, with Kendrick 0-1 with a 2.19 ERA in the season series.