Francisco Alvarez hit a walk-off homer in the ninth inning on Monday night for the host New York Mets, who earned a 4-3 win over the Baltimore Orioles in the opener of a three-game interleague series.

Orioles relievers Colin Selby, Keegan Akin and Seranthony Dominguez (3-3) set down 11 straight Mets — nine by strikeout — before Alvarez hit a 3-0 fastball over the center field fence.

Alvarez dropped his bat and motioned toward the Mets’ dugout before embarking on his trot around the bases following his first career walk-off homer.

Edwin Diaz (4-1) logged a perfect ninth inning for the Mets, who won for the fourth time in 10 games to move within 1 1/2 games of the idle Atlanta Braves in the race for the final National League wild-card spot.

Ramon Urias and Ryan Mountcastle had two hits apiece while combining to score all three runs for the Orioles, who fell a half-game behind the idle New York Yankees in the race for first place in the American League East and the top overall seed in the AL.

J.D. Martinez hit a two-run homer in the first against Baltimore starter Trevor Rogers, and Tyrone Taylor laced an RBI single in the fourth for the Mets. After Taylor reached, New York didn’t have another hit until Alvarez’s homer.

Three other Mets — Mark Vientos, Pete Alonso and Starling Marte — each had one hit.

Urias raced home on a groundout by Jackson Holliday in the fifth before he capped a unique sequence against Mets starter David Peterson in the seventh. Peterson balked home Mountcastle and gave up a game-tying solo homer to Urias on the next pitch, making it 3-3.

Rogers allowed three runs on five hits and three walks while striking out five over 4 2/3 innings. Peterson gave up three runs (two earned) on six hits and one walk while striking out eight over a season-high seven innings.

–Field Level Media