Edwin Diaz got into and out of a none-out, bases-loaded jam in the ninth inning Friday night to close out a 5-4 win for the New York Mets over the host Cincinnati Reds in the opener of a three-game series between the National League wild-card contenders.

The Mets (76-65), who entered Friday with a four-game lead over the San Francisco Giants in the race for the last wild card, won for the third time in four games.

The Reds (70-71) fell to an NL-worst 6-13 since Aug. 15 and dropped six games behind the Mets. Cincinnati also slipped under .500 for the first time since it was 32-33 on June 7.

The Mets led 4-0 and 5-1 before the Reds scored three times in the fourth against David Peterson (9-5). Ryne Stanek, Brooks Raley and Tyler Rogers combined for 2 2/3 innings of one-hit ball before Cincinnati loaded the bases against Diaz, who gave up a leadoff single to Ke'Bryan Hayes before walking Matt McLain and TJ Friedl.

Diaz then struck out Noelvi Marte and Elly De La Cruz. Gavin Lux pulled a potential game-winning extra-base hit just foul down the first base line two pitches before his grounder in between first and second eluded Pete Alonso. But Luisangel Acuna, backing up the play, fielded the ball and threw to Diaz covering to close out the reliever's 26th save.

Mark Vientos was 2-for-4 with a homer and two RBIs for the Mets. He is batting .324 with nine homers and 24 RBIs in his last 18 games after hitting .227 with just seven homers and 32 RBIs in his first 83 games through Aug. 16.

Juan Soto was 2-for-4 with an RBI double while Starling Marte had an RBI single and Brandon Nimmo lofted a sacrifice fly.

Peterson gave up the four runs on seven hits and one walk while striking out four over 5 1/3 innings.

Tyler Stephenson had a two-run double off Peterson, who also surrendered sacrifice flies to Noelvi Marte and Hayes.

Andrew Abbott (8-6) took the loss after allowing all five runs on nine hits and one walk while striking out five over 4 2/3 innings.