Hours after Terry Collins took a leap of faith and handed a hitless Lucas Duda the Mets’ starting first base job, Duda gave his manager a pair of towering two-run home runs and his team its first win of the year.

Duda was given the first base job Friday afternoon, and proceeded to club two-run shots in the fourth and sixth innings Friday night. His power and Jenrry Mejia’s strong start gave the struggling Mets bullpen a lead even it couldn’t blow in a 4-3 win over Reds.

“It’s great to certainly have him step forward and step up, and do what he did. We needed it as a team immensely. So I salute him,’’ Collins said of Duda, who helped the Mets avoid losing their first four at home for the first time since 1992. “It’s really big. These guys, they’re not just out there playing: They want to win. … We’ve just got to stay confident, stay upbeat, realize we’ve got a long way to go. But this win was huge for us.’’

Mejia (1-0) allowed just one run in six strong innings. And after the bullpen had pitched to a bloated 10.61 ERA in suffering a three-game sweep at the hands of the Nationals, nominal closer Jose Valverde fanned Jay Bruce with two on and two out to seal it. But it was Duda who stole the show.

“Yeah, that was definitely nice,’’ Duda said. “We got swept by the Nationals at home. They’re a great team, tip your hat. But we’ve got some things to turn around, and hopefully we can continue to play well and build on this win.’’

Duda came in 0-for-6 with three strikeouts, but after starting three different first basemen through the first three games — and losing all three games — Collins made the call to hand Duda the job. It was nervy since Ike Davis is both popular in the clubhouse and unhappy with the decision. But for Friday it paid off.

“It was a supposed competition, so there was going to be a winner and there’s only two choices,” Davis said. “It wasn’t so surprising.’’

In the fourth inning, after Curtis Granderson saw a shift and poked a double down the third-base line, Duda put the next pitch from Mike Leake (0-1) into the bullpen for a 2-1 lead. In the sixth, he followed David Wright’s leadoff infield single by crushing Leake’s 2-1 pitch out to right for a 4-1 cushion.

It was Duda’s fifth career multi-homer game, and after only hitting two homers all last season with men on base, it was as auspicious an audition as one could have hoped for.
And for a change the bullpen held a lead. Barely.

On a cold, wet night, the 24-year-old Mejia — who said he could barely feel his fingers at times — walked five, one right after getting hit on the right leg by a Brandon Phillips liner. But with a nasty slider and improved changeup, he struck out a career-high eight, including Leake on an 81 mph slider with men on the corners to end both the sixth, and his night.

“The conditions were brutal. He made big pitches when he had to,’’ Collins said. “It was tough to grip the ball, but he hung in there when he had to.’’