CINCINNATI — David Peterson’s mediocre outing melded with an offensive attack that stalled after an early eruption, leaving the Mets in a precarious position Friday night.

Manager Carlos Mendoza’s bullpen, entrusted with a one-run lead, wouldn’t have the luxury of a cushion.

But a relief crew that has hardly dominated in the manner that was projected — after three trade deadline acquisitions — executed, allowing the Mets to escape with a 5-4 victory over the Reds at Great American Ball Park.

Edwin Diaz pulled a Houdini by retiring three straight batters with the bases loaded in the ninth without a run scoring.

His final act was racing to cover first base to receive Luisangel Acuna’s throw on Gavin Lux’s grounder, ending the game.

Diaz struck out the previous two batters, Noelvi Marte and Elly De La Cruz, after surrendering a single and two walks to begin the inning.

The Reds, desperate for wins to stay afloat in their pursuit of the NL’s third wildcard, fell six games behind the Mets in that race.

The Giants, sandwiched in between the two teams — they began the night four behind the Mets — played a later game.