With the win, the Phillies maintained a three-game lead over Atlanta in the NL East and improved to 28 games over .500 for the first time since 1993.

Philadelphia can help its chances for a fourth consecutive division title beginning Monday night, when the Braves come to town for a three-game series.

The Phillies will send Cole Hamels to the mound against Braves starter Jair Jurrjens in the opener followed by Roy Halladay and Roy Oswalt. The three Phils starters are a combined 10-0 with a 2.21 ERA with 71 strikeouts in September.

Mike Minor and Tommy Hanson will also start for Atlanta.

"We're not going in overconfident or anything," Howard said. "We are just going to try to continue to do things the way we've been doing them. We know how everyone looks at this series and the importance of if, but we just have to maintain our focus and just go out and play."

In the ninth, Nationals rookie closer Drew Storen (3-4), who has blown two of six save opportunities this year, entered with a three-run lead and six consecutive scoreless innings under his belt. That soon changed as Placido Polanco singled and Chase Utley doubled into the left field corner.

"Polanco did a great piece of hitting on a quality pitch," Nationals manager Jim Riggleman said. "Then the big boys came up."

Howard followed with his two-run single and the Phillies trailed 6-5 with no out and a runner on first.

"They had us kind of dead in the water until the last inning," Howard said. "Polly got a hit, Chase got a hit and we kind of got life from there. I was just going up there to try to keep it going and at least get one run home."

Werth, who had three hits, three RBIs and a pair of runs scored, got ahead 2-0 but Storen fought back to a full count.

"[Storen] was challenging [Werth]," Phillies manager Charlie Manuel said. "And Werth hit one out."

"I got in a good count but chased ball four," said Werth, who hit the second walk-off homer of his career, the first coming on July 21, 2009, off of Chicago's Jeff Samardzija. "I had to battle and fouled off a slider. After that, I just looked for a good pitch to hit and see it."

Vance Worley (1-1) pitched an inning for the win.

The Nationals took control with a three-run rally against Phillies starter Joe Blanton in the sixth inning. Ian Desmond led off the inning with a single to right field. After a lineout to left, Desmond stole second and Adam Dunn walked. Roger Bernadina popped out to short and Desmond, who was attempting to steal third, had to scamper back to second.

Michael Morse then hit a cutter to right-center for his 11th home run of the season that gave the Nationals a 4-3 lead.

Danny Espinosa and Willie Harris also homered for the Nationals.

Werth has hit .360 over his last six games with 10 RBIs, nine runs scored on four home runs.

Game notes
Washington OF Nyjer Morgan invited the fan he was accused of hitting with a ball in August at Citizens Bank Park to the game, according to the Nationals public relation staff. Morgan gave the fan a free ticket behind the Nationals' dugout on Sunday. The two met before the game on the field and Morgan also brought him into the clubhouse to meet his teammates and coaching staff. .... With an announced sell-out crowd of 44,936 the Phillies extended their streak of consecutive sellout at Citizens Bank Park to 117. . . Phillies centerfielder Shane Victorino, who was ejected in the sixth by third base umpire Angel Hernandez, went 0-for-4 and had an 11-game hitting streak come to en end.