WASHINGTON -- Bartolo Colon decided before the game Monday that he was going to keep the bat on his shoulder when he was at the plate to be sure he did not aggravate his back.

"I am not going to swing," the New York Mets right-hander told Washington Nationals catcher Wilson Ramos after he saw a changeup early in the game.

Colon certainly caused enough damage on the mound, as he allowed just one run on five hits (all singles) in seven innings, and the Mets beat the first-place Nationals 7-1.

Colon (4-3) allowed 11 runs in his previous three starts. He struck out two and walked two Monday.

"This is the best he has pitched; great command of his stuff. I am not sure if he threw 10 off-speed pitches," Mets manager Terry Collins said. "Maybe he is back on that run again."

Meanwhile, Nationals starter Gio Gonzalez (3-2) endured his worst outing of the season. He gave up a season-high seven runs on 10 hits in five innings as he ERA rose from 1.86 to 2.87.

The lefty from Miami said it was just a coincidence that Ramos was back of the plate for the first time this year as his catcher. Jose Lobaton, the Washington backup catcher, normally catches Gonzalez this year.

"I was just missing up. It is unfortunate I was flat today," Gonzalez said. "It was just one of those days."

Gonzalez gave up a three-run homer to David Wright in the third inning and back-to-back shots to Yoenis Cespedes and Neil Walker in the fifth. Wright has been playing through back problems.

"This guy is a good baseball player," Collins said of Wright. "I think he feels good."

Those homers came just hours after the Mets -- who lead the majors in homers -- learned that first baseman Lucas Duda will be out several weeks with a lower back injury.

"We are going to miss this guy," Collins said of Duda. "He is a dangerous hitter, and these teams know it. He scares the other teams when he walks up there. It is nice we have some depth, but we are going to miss him.

"I think we are going to hit. I think we are going to get it going."

Washington couldn't get it going Monday against Colon, former Nationals lefty Jerry Blevins and Logan Verrett. The trio allowed just six singles.

Bryce Harper went 0-for-4 as his average fell to .252. Harper has 48 walks in 44 games, but he did not draw a free pass Monday.

"I saw Barry (Bonds) get one or two pitches a night (to hit)," said Washington manager Dusty Baker, the skipper for Bonds in San Francisco.

Wright had three RBIs, while Curtis Granderson, Juan Lagares, Cespedes, Walker and former National infielder Asdrubal Cabrera each had two hits for the Mets. The Nos. 4-5-6 hitters for New York combined for six hits, four runs and three RBIs.

New York (26-18) won its fourth game in a row while Washington (27-18) saw its lead shrink to a half-game over the Mets in the National League East.

Daniel Murphy, Jayson Werth and Ryan Zimmerman each had two hits for the Nationals, who have lost six of their past 10 home games.

New York had five hits in a row while scoring five runs in the third. Wright hit a three-run homer on the first pitch he saw from Gonzalez, Cabrera had an RBI single, and Eric Campbell drove in the fifth run on a hard sacrifice fly to make it 5-1.

The Nationals had three singles in the first inning, the last one by Zimmerman driving in Werth to make the score 1-0. Washington now has 48 first-inning runs this year to lead the majors.

Gonzalez allowed seven runs on 10 hits (including three homers) with seven strikeouts in five innings before Blake Treinen took over in the sixth. Gonzalez entered the game with a 1.86 ERA -- the best mark among Washington starters. Prior to Monday, he was 10-4 in his career in 18 starts against the Mets.

"Gio had been pitching great," Collins said. "David's homer really kick-started us."

NOTES: The start of the game was delayed one hour, seven minutes by rain. ... Mets 1B Lucas Duda went on the 15-day disabled list due to a stress fracture in his lower back. "He will be out for a while," said Mets manager Terry Collins. UT Ty Kelly was called up from Triple-A Las Vegas, and the Mets designated LHP Dario Alvarez for assignment. ... The series continues Tuesday with Washington RHP Stephen Strasburg (7-0, 2.80) facing Mets RHP Matt Harvey (3-6, 5.77), who gave up a career-high nine runs (six earned) in his start against Washington on Thursday in New York. Harvey lasted a career-low 2 2/3 innings ... Mets RHP Noah Syndergaard was named the National League player of the week for May 16-22. He was 2-0 and didn't allow an earned run in 14 innings, with no walks and 21 strikeouts. ... Washington 2B Daniel Murphy, who played for the Mets for seven years through 2015, leads the majors with a .389 average.