WASHINGTON -- Kyle Schwarber homered three times and tied a major league record with five in a two-game span, leading the Washington Nationals over the New York Mets 5-2 Sunday to take three of four in the series.

Schwarber set a Nationals/Montreal Expos record by homering nine times in a 10-game span, increasing his total to 18 this season with his first career three homer-game. Schwarber is the second player in Nationals/Expos franchise history with five home runs in a two-game span, joining Bryce Harper, who accomplished the feat in 2015.

Schwarber also joins Mookie Betts as the only leadoff hitters to hit five home runs in a two-game span in the modern era (since 1900). Betts did it vs the Baltimore Orioles in 2016.

Moved in the leadoff spot on June 12, Schwarber had four RBIs for the second straight game.

"To be honest with you, I don't know what's going on,'' Schwarber said.

He hit a 2-0 fastball from Taijuan Walker (6-3) for his fourth leadoff home run this season, capped an eight-pitch at-bat starting the fifth by homering on a sinker for a 3-1 lead.

"I think he's just locked in right now,'' Walker said. "He was just hitting every fastball we threw at him.''

Schwarber then hit an 0-1 slider from Jeurys Familia for a two-run homer into the Mets' bullpen in left field in the seventh.

"That's as hot as you can get,'' Mets manager Luis Rojas said.

Schwarber had the sixth three-homer game since the franchise moved to Washington for the 2005 season, the first since Anthony Rendon's 10-RBI game against the Mets on April 30, 2017.

"I'm a big believer that hitting is a feeling. Don't get me wrong, there's mechanical, there's approach, things like that,'' Schwarber said. "But when you step in the box and everything feels right, you already have a big advantage.''

Schwarber's third homer followed a pinch-hit double by Gerardo Parra, a 34-year-old fan favorite who returned to the Nationals on Sunday when his contract was selected from Triple-A Rochester. Parra's walkup music of the children's song "Baby Shark'' became a theme of the Nationals' run to the 2019 World Series title, and it sounded before his at-bat to the crowd's delight.

Parra spent last season with the Yomiuri Giants in Japan, then signed a minor league contract with the Nationals last winter.

"Almost cried,'' Parra said of the crowd reaction.

The Associated Press contributed to this report.