When Terry Collins moved Michael Conforto to the third slot in the batting order, he left open the possibility of moving him against a left-hander.

Conforto ripped three more hits Monday night’s 5-3 victory over Cincinnati – including a homer in the first – but with left-hander Brandon Finnegan going Tuesday for the Reds, what will Collins do?

CONFORTO: Sizzling. (AP)

Here’s hoping he lost his righty-lefty book and keeps Conforto batting third. Most importantly, you don’t want Collins messing with a hot hitter and giving even the slightest hint of not having complete confidence in Conforto against left-handers.

Maybe, against Clayton Kershaw and Madison Bumgarner – the Giants are in this weekend – Conforto might move, but against Finnegan?

That would make no sense.

In going 3-for-3 with a walk, Conforto is hitting .378 (14-for-37) with eight runs scored, five doubles, three homers and eight RBI since moving to the No. 3 spot. He’s hitting .333 overall without even a whisper of a reason why he should be moved.

Even if Yoenis Cespedes can play Tuesday, Conforto should stay third. He said he’s always hit third and relishes the role. Those aren’t reasons why he should stay there. He should stay because he’s the best player for that role, even over Cespedes.

Tell me, the Mets have a runner on third with one out, who would you rather have at the plate, Cespedes of Conforto?

“It’s where you want to be,’’ Conforto told reporters about hitting third. ““You have to be a guy who uses the whole field,’’ Conforto said. “You have to have a good [hitting] zone and be able to shrink that and you want to be a guy who tends to hit well in big situations, a guy who drives runs in, you have to make sure those situations don’t get too big.’’

Third is the spot where a team traditionally bats its best hitter. Ted Williams, Mickey Mantle and Willie Mays usually hit third in another era, as did Keith Hernandez for the 1986 champion Mets. Barry Bonds and a healthier David Wright most recently flourished hitting third.

I’m not saying Conforto will turn into an elite player like them – in his wildest dreams he probably hasn’t considered it – but he is the Mets’ best overall hitter.

“He drove in big runs, that’s why he’s hitting third,’’ Collins said.

Conforto spent a lot of time this winter working on situations a No. 3 would face, such as pulling inside fastballs; cutting down his hitting zone on specific counts; and hitting the ball on the ground or in the air depending on the game situation.

Collins said Conforto would likely be the Mets’ long-term No. 3 hitter. Don’t change things now.

METS GAME WRAP

 Game: #18 Record: 11-7 Streak: W4

SUMMARY: Noah Syndergaard labored most of the night, but home runs from Conforto, Lucas Duda and Neil Walker gave the Mets their fourth straight victory.

KEY MOMENT: Walker’s two-run homer in the seventh. When the Mets were on defense in the eighth fans chanted Walker’s name. Sweet.

THUMBS UP: Two hits, including a two-run homer in the third from Lucas Duda. … Logan Verrett struck out Ivan De Jesus with the go-ahead runner on third to end the seventh. … A 1-2-3- eighth in relief from Addison Reed. … Twelve strikeouts from Mets’ pitchers, including nine from Syndergaard. … A 1-2-3 stress-free ninth from Jeurys Familia.

THUMBS DOWN: The Reds stole five bases against the Syndergaard-Travis d’Arnaud battery. … Antonio Bastardo had a blown save. … Mets’ hitters struck out 10 times. … An 0-for-4 night from Wright with two strikeouts. … They were 1-for-9 with RISP. … d’Arnaud left the game with a sore right shoulder. Collins said it is too early to project it being a DL situation.

EXTRA INNINGS: The homer was Walker’s eighth of the month, the most he’s ever hit in a month. … The Mets have won nine of their last 11 games. … They have scored in the first inning in eight of their last ten games. … They’ve won nine straight against the Reds.

QUOTEBOOK: “That was pretty awesome,’’ Walker on he crowd chanting his name after his homer.

BY THE NUMBERS: 28: Mets’ homers in 18 games.

NEXT FOR METS: Bartolo Colon (1-1, 2.89) starts for the Mets against Reds’ Finnegan (1-1, 3.74). Colon gave up three runs in six innings with a no-decision in his last start, April 20, at Philadelphia. Colon in 4-1 with a 3.77 ERA in five career starts against the Reds.