WASHINGTON -- There is not a whole lot of stability these days in the pitching rotation of the Washington Nationals, who nonetheless could run away with the National League East title.

Star right-hander Stephen Strasburg left his start after 42 pitches Wednesday with a flexor mass strain, and manager Dusty Baker wouldn't reveal which hurlers would get the nod on Monday and Tuesday against the second-place New York Mets.

Thus, that adds importance to veteran left-hander Gio Gonzalez, who bounced back from an ugly start to beat the Philadelphia Phillies 3-2 on Sunday afternoon.

The durable Miami-area native went seven innings and allowed just one run and four hits as he lowered his ERA to 4.27.

"He was dealing," Baker said. "He had that changeup working. He was ahead in the count most of the time with his fastball. It was well-located and he seemed like a guy on a mission. We talked the other day and I told him that he's very important in this equation, especially with Stras out and he responded."

Gonzalez is 11-9 and has won at least 10 games every year since 2010. He has made 29 starts this year and has recorded at least 27 starts in all five seasons in Washington.

"My last start didn't go that way," said Gonzalez, who gave up six runs and eight hits in just three innings on Tuesday against the Atlanta Braves. "A good bounce back. I just wanted to have a good bounce back. As long as I can keep going deep in the game (that is important)."

Anthony Rendon broke a tie with an RBI double in the seventh for Washington, now 14-5 against the Phillies this year despite getting just four hits Sunday.

The Nationals (85-58) started the day nine games ahead of the Mets in the NL East. The Phillies (63-80) lost three of four games in the series.

"They can't say we are a pushover," said Phillies manager Pete Mackanin, who was pleased with his young pitchers in the series. "Our starters really battled. Really a good sign."

Bryce Harper walked to lead off the seventh against lefty starter Adam Morgan (2-10) and then scored on the double with no outs to left-center by Rendon, who leads NL third basemen with 37 such hits. The Nationals got a break as the Rendon hit off reliever Edubray Ramos nearly bounced over the wall for a ground-rule double, which would have kept Harper at third.

"He is a very, very Important cog in our lineup," Baker said of Rendon. "That No. 5 hitter is one of the most important in the lineup."

Rendon scored to make it 3-1 on a passed ball by catcher A.J. Ellis on a pitch from Ramos.

"I think the ball just took off," Mackanin said.

The Phillies cut the lead to 3-2 when Freddy Galvis led off the eighth with a solo homer on the first pitch from rookie reliever Koda Glover. Later in the inning, Cesar Hernandez had his second single of the game, off Blake Treinen. After a walk to Roman Quinn, who was making his MLB debut, Treinen induced a double play grounder by Andres Blanco to end the inning.

Closer Mark Melancon pitched the ninth for the Nationals and got his 11th save since he was traded to Washington from the Pittsburgh Pirates in late July.

Tommy Joseph of the Phillies hit a 3-1 pitch over the fence in center to tie the game at 1 off Gonzalez in the seventh. Gonzalez had retired nine batters in a row before Joseph hit his 18th homer.

"We just don't seem to put hits together," Mackanin said. "We are not winning these games. We just need some professional hitters in the middle" of the order.

The Nationals took a 1-0 lead in the first as Trea Turner led off with a single and scored on a double by Daniel Murphy off Morgan. The lefty-hitting Murphy extended his career high for doubles (42) and RBIs (102).

Hard-luck loser Morgan allowed two runs in six innings and is now 1-10 in his last 15 starts.

Turner had two hits and two steals for the Nationals, who are 45-19 against the other members of NL East. That is the most wins of any team in its own division.

The Nationals have won their last five games decided by one run.

"Guys made some great plays," Gonzalez said. "Also timely hitting came in. A big double for Rendon. Everyone did their job."

NOTES: To mark the 15th anniversary of the Sept. 11 terror attacks, Secretary of the Navy Ray Mabus threw out the first pitch, local first responders were recognized and the U.S. Naval Academy Men's and Women's Glee Club & Gospel Choir performed the national anthem. ... The Phillies recalled C Jorge Alfaro and OF Roman Quinn from Double-A Reading after that minor-league team had its season end Saturday in the Eastern League playoffs. Quinn was in the starting lineup at center field to make his big league debut and he grounded out in the first inning in his first at-bat. ... Phillies RHP Jeremy Hellickson (10-9, 3.90) will face Pirates RHP Gerritt Cole (7-9, 3.55) on Monday in Philadelphia. ... Washington starting LHP Gio Gonzalez played in the Phillies' system for Double-A Reading in 2006. He posted a 7-12 mark in 27 starts.