CINCINNATI — Jacob deGrom’s chances of winning the NL Cy Young award appear much greater than the Mets’ playoff odds, but that doesn’t mean the pitcher and his team can’t dream the dream.

Friday night the stud right-hander ran his scoreless streak to 16 innings, keeping the Mets — who have little room for error — from sinking in the NL wild-card race.

In case that wasn’t enough for one night, Pete Alonso slugged homer No. 50 in an 8-1 victory over the Reds at Great American Ball Park.

The victory was a third in four games for the Mets, who remained 3 ½ games behind the Brewers in the race for the NL’s second wild card.

Alonso’s two-run rocket in the eighth off Sal Romano was the knockout punch, giving the Mets a five-run lead on a night when deGrom fired seven shutout innings in which he allowed four hits and struck out nine. DeGrom’s ERA dropped from 2.61 to 2.51 as he battles Hyun-Jin Ryu, Mike Soroka and Max Scherzer, among others, in the Cy Young race. Ryu began the night as the NL leader in ERA at 2.35.

“Personal goals, everybody sets them, but the more important thing is for the team,” deGrom said. “And getting to the playoffs is the main goal, and hopefully getting to that wild-card game and having a chance to win that and move on.”

DeGrom said he alerted manager Mickey Callaway he was fatigued after completing the seventh at 96 pitches. During his pregame bullpen session, deGrom said he wasn’t as sharp as normal.

“Once I got out there I felt pretty good, but warming up I didn’t feel great,” deGrom said.

Brad Brach, Luis Avilan, Edwin Diaz and Jeurys Familia combined to pitch the final two innings. The struggling Diaz retired the only batter he faced, striking out Eugenio Suarez to end the eighth with two runners on base.

Alonso needs only two homers to tie Aaron Judge’s rookie record. Alonso is two ahead of Suarez for the MLB lead in homers.

“I don’t think this is truly going to settle in until I take time to reflect in the offseason,” Alonso said.

Among his notable achievements, Alonso reached 50 career homers faster than any other player in MLB history (152 games).

“He’s a wonderful player,” Callaway said. “He’s a leader in every sense of the world and he’s a leader on the field as well with the 50 homers.”

Reds ace Luis Castillo was a formidable foe, but the right-hander cracked in the later innings. Overall, he went seven innings and allowed three earned runs on three hits with seven strikeouts and three walks.

Castillo had allowed only two homers in his previous five starts combined, but Jeff McNeil and Amed Rosario equaled that with a blast apiece, accounting for the Mets’ runs before Alonso homered. McNeil’s homer was his eighth in 23 games since returning from the injured list.

Rosario gave the Mets a cushion with a two-run homer against Castillo in the seventh that extended the lead to 3-0. With two outs, J.D. Davis walked before Rosario cleared the fence in left-center for his 14th homer of the season.

McNeil’s homer in the sixth was only the Mets’ second hit against Castillo and gave them a 1-0 lead. The blast was McNeil’s 23rd of the season and third on the road trip.

Castillo had plowed through five innings, allowing only a single to Wilson Ramos in the second and walks to Brandon Nimmo and Michael Conforto in the third and fifth innings, respectively.

The biggest early threat against deGrom came in the fourth, when Aristides Aquino singled and stole second with one out. But deGrom retired the next two batters to keep the game scoreless.

“He’s our ace for a reason,” Alonso said. “He absolutely carved tonight.”

In each of his past two starts, deGrom has been gassed after seven innings, but Callaway said it’s not a concern.

“It’s a long season,” Callaway said. “These guys have been working so hard and pitching every fifth day for the most part. There will be a time, hopefully we will get to there, where you throw all of that aside and just keep on going, but he is doing his job, that is for sure.”