Mets' Rajai Davis is greeted at the dugout after his...

Mets' Rajai Davis is greeted at the dugout after his three-run double against the Los Angeles Dodgers during the eighth inning of an MLB baseball game at Citi Field on Saturday, Sept. 14, 2019. Credit: Kathleen Malone-Van Dyke

First there was a battle of arms between Jacob deGrom and Hyun-Jin Ryu on Saturday night at Citi Field.

When that matchup didn’t produce a single run for either team, the game came down to a battle of wits between managers Mickey Callaway and Dave Roberts.

On this night, Callaway came out on top and so did the Mets, 3-0, on pinch hitter Rajai Davis’ three-run double with two outs in the eighth inning.

The game was scoreless into the eighth thanks to deGrom and Ryu, who each threw seven shutout innings. Before Seth Lugo struck out the side in the top of the eighth, Callaway had double-switched the righty into the second spot in the batting order in an attempt to use his hottest reliever for two innings.

Funny thing is, the Mets loaded the bases with two outs in the eighth, which brought up Lugo’s spot. With J.D. Davis switched out of the game, Rajai Davis got the call

against lefthander Julio Urias and lined a three-run double into the leftfield corner. Callaway outfoxed the 2016 NL Manager of the Year and the Mets remained three games behind the Cubs in the race for the NL’s second wild card spot.

The way the bases got loaded was interesting. Roberts started the inning with lefthander Adam Kolarek, who struck out Robinson Cano. Roberts brought in righthander Joe Kelly to face Todd Frazier, who got hit on the left elbow with the first pitch. After Kelly struck out Juan Lagares for the second out, Roberts brought in Urias, who hit Brandon Nimmo with a pitch.

Urias walked Amed Rosario to load the bases for Davis, who came in with a .154 average and four RBIs as a Met. Now he’s hitting .200 with seven RBIs — six of them as a pinch hitter.

“It’s huge,” Davis said. “It means maybe I get more opportunities. But I’m just happy that I could help us win today.”

Why did Callaway choose Davis? He didn’t want to use Michael Conforto against the lefty. The other available righty swingers were switch hitter Jed Lowrie, who is hitless in three at-bats this season, and backup catchers Rene Rivera and Tomas Nido.

So Davis it was. Callaway said batting coach Chili Davis made the observation that Urias is a high-ball pitcher and Rajai Davis is a high-ball hitter.

“That allowed him to foul a couple of those [high fastballs] off and then he got one in the zone he could handle,” Callaway said. “You always consider everybody and then make the best choice from there.”

It’s been an up-and-down (mostly down) season for Davis, 38, who is in his second stint with the Mets.

On May 22, he had a memorable pinch hit three-run home run after getting called up earlier in the day and taking a $243 Uber ride from Allentown, Pennsylvania, to Citi Field.

“Early, I had some real aggressive swings,” Davis said. “When I got to two strikes, I was just trying to put a ball in play and let the ball travel. Get a pitch I could handle, try to put it in play and see what happens.”

Here’s the problem with chasing a team that plays a lot of games during the day: The Mets knew the Cubs had beaten the Pirates, 14-1, on Saturday afternoon before they took the field.

Was it a must-win?

“I think so,” Callaway said. “We’re at that point where every game is very important. They have been important for a while and they’ll continue to be important. So we have to do everything we can to win every night.”

DeGrom, last year’s Cy Young Award winner, allowed three hits, hit one batter and struck out eight. He left after 101 pitches.

Ryu, the NL’s leader in ERA, allowed two hits and struck out six. He left for a pinch hitter after throwing 90 pitches and lowering his ERA to 2.35.