PHILADELPHIA -- Facing familiar hitters, John Lannan was at his best.
Lannan (2-3) had four strikeouts in his longest outing in four years. The lefty registered 12 groundouts to beat the team he played for his first six seasons in the majors.
"At this point, I'm looking for consistency," he said. "It doesn't matter who I'm facing. I have to put up zeroes. That's what I have to do, keep the ball on the ground. I'm not a strikeout guy."
Jonathan Papelbon allowed two runs in a shaky ninth to earn his 19th save in 23 tries.
Dan Haren (4-10) came off the disabled list and took the loss after missing two weeks because of right shoulder inflammation. Haren allowed two runs and seven hits in five innings, striking out a season-high seven.
"I think the time off helped me to clear my head," said Haren, who is 0-7 with a 6.66 ERA in his last nine starts.
Revere and Jimmy Rollins, the 1-2 hitters in Philadelphia's lineup were 5 for 9 with three runs and one RBI.
The Phillies opened an important four-game set against second-place Washington with their fifth win in seven games. They won consecutive series against first-place clubs, taking two of three from Pittsburgh and Atlanta.
"We got to keep playing, stay with it, manager Charlie Manuel said.
While Lannan downplayed beating his ex-teammates, Manuel figured his pitcher was fired up.
"I think it's kind of natural," Manuel said. "I know I would be. I might be jumping up and down."
The Nationals had won four in a row.
Bryce Harper, chosen earlier in the day to participate in the Home Run Derby next week, led off the ninth with his second hit. After Ryan Zimmerman hit a double, Jayson Werth hit a sacrifice fly. Adam LaRoche's sac fly cut it to 3-2 before Papelbon retired pinch-hitter Chad Tracy to end it. Tracy hit a tying homer off Papelbon in the ninth inning on June 17, but the Phillies rallied to win that one.
"We made a nice comeback against one of the best closers in the league," Nats shortstop Ian Desmond said.
Making his first start since June 22, Haren struggled in the first.
Revere and Rollins started Philadelphia's first with consecutive singles followed by a double steal. After Chase Utley struck out, Domonic Brown drove in a run with a single off Haren's leg. A bases-loaded walk to Darin Ruf forced in the second run.
"We just have to continue to do the little things, especially with Ryan out of the lineup," Brown said. "We got guys with speed on base, making things happen."
It stayed 2-0 until the sixth.
Revere hit a two-out double and scored on Rollins' line-drive single to right. Revere slid in safely ahead of Jayson Werth's strong throw and nearly kicked Utley in the face doing a backward kick-stand getting up after the slide.
Revere has raised his average to .300 from .200 on May 1.
"I feel a lot more comfortable at the plate," Revere said.
Phillies 1B Ryan Howard will have surgery for a torn meniscus in his left knee and is expected to miss six to eight weeks. ... Phillies P Roy Halladay is making progress in his recovery from shoulder surgery. Halladay is throwing off flat ground from 75 feet. ... Lannan last went eight innings for Washington in a 3-2 loss at St. Louis on Aug. 28, 2009. ... Newly acquired outfielder Scott Hairston had travel delays leaving Chicago and arrived late to the ballpark. Hairston gives the Nationals a veteran right-handed hitter with power off the bench. "We just wanted a little bit more pop on the right side, a guy who can handle some left-handed pitching," Nats general manager Mike Rizzo said. ... OF/1B Tyler Moore was optioned to Triple-A Syracuse to make room for Haren. ... Cole Hamels (3-11, 4.38) faces Taylor Jordan (0-1, 2.70) on Tuesday night.