PORT ST. LUCIE, Fla. — In these waning days of spring training, the Mets want to be sure.

Manager Carlos Mendoza & Co. have not disclosed decisions on the final few roster spots. In some cases, that probably will go right down to Wednesday, Opening Day Eve, he said. The Mets intend to bring several players with them to Houston on Monday night who may or may not be on the roster come Thursday.

That allows for the possibility of a late addition, probably a waiver claim of a fringe player another club didn’t have room for. Such a move could bump, say, infielder Luisangel Acuna or catcher Hayden Senger.

“A lot can happen,” Mendoza said. “It’s not an easy situation as a player, but it’s part of the business and we were pretty honest with them. They’re going to get on that plane and we’ll see what we got.”

The Mets informed relievers Chris Devenski, Genesis Cabrera and Jose Urena, as well as catcher Jakson Reetz and infielder Donovan Walton, that they will not make the team, Mendoza said.

Based on those cuts and other goings-on in Mets camp, let’s project the Mets’ season-opening roster.

LINEUP (9)

1. SS Francisco Lindor
2. RF Juan Soto
3. 1B Pete Alonso
4. LF Brandon Nimmo
5. 3B Mark Vientos
6. DH Jesse Winker
7. 2B Brett Baty
8. C Luis Torrens
9. CF Jose Siri

With the Astros pitching lefthander Framber Valdez in the opener on Thursday, the righthanded-hitting Acuna may well draw the start. But Baty, who isn’t officially on the club yet, should get the majority of the time at second while Jeff McNeil (right oblique strain) is out, whether that be in a platoon or as the straight-up starter.

An interesting bit of minutia: Without McNeil and Francisco Alvarez (broken bone in hand), the bottom third of the lineup is far less deep. When Siri is in there over Tyrone Taylor, will Siri — who has batted .203 but averaged 21.5 home runs the past two years — get moved up? Or will the Mets leave him ninth? Even with injuries, he remains intriguing in the last spot as a so-called second leadoff hitter.

ROTATION (5)

1. RHP Clay Holmes
2. RHP Tylor Megill
3. RHP Griffin Canning
4. LHP David Peterson
5. RHP Kodai Senga

The only uncertainty here is whether the Mets go with Megill or Paul Blackburn. Consider Megill, who allowed three runs in 5 1⁄3 innings Saturday against the Nationals, the favorite. Blackburn pitched in a minor-league game at the same time.

“It’s not my decision, but I think I had a good spring,” Megill said. “A lot of positives. Just waiting around, seeing what happens. I feel like I had a really good spring. The stuff is there, not a lot of hard contact, putting the ball in play. Overall, I thought it was good.”

The Mets slotted Senga last — an April 1 debut in Miami — to give him as much time as possible to get ready after missing almost all of last season because of injuries. He will stay back in Florida to pitch in a minor-league scrimmage Wednesday.

BENCH (4)

1. OF Tyrone Taylor
2. OF/DH Starling Marte
3. IF Luisangel Acuna
4. C Hayden Senger

Acuna and Senger are in purgatory. They are the last players in camp competing for openings at their positions, but the Mets aren’t ready to give them anything. The two will have to wait to see if the Mets bring in a last-minute replacement.

Snagging a spot would be especially sweet for Senger, 27, the Mets’ 24th-round draft pick in 2018. He has steadily climbed the minor-league ladder ever since, earning high marks for his defensive work.

BULLPEN (8)

1. RHP Edwin Diaz
2. RHP Ryne Stanek
3. LHP A.J. Minter
4. RHP Reed Garrett
5. RHP Jose Butto
6. LHP Danny Young
7. RHP Paul Blackburn
8. RHP Max Kranick

Slow spring training progressions for Minter and righthander Dedniel Nunez, who are coming off injuries last year, have yielded uncertainty.

Minter is in very good shape to be ready. He pitched Saturday and is scheduled to pitch Monday, checking off the two-out-of-three-days box, which Mendoza highlighted as important. Given the Mets’ early off days — two in the first eight days and three in the first 15 — Minter should be able to ease in just fine.

Nunez, whose scheduled appearance Monday would be only his third, seems more likely to start the year on the injured list. An extra two weeks to get ready would do him a lot of good, and it would allow the Mets to take a look at another interesting arm.

Blackburn in the bullpen as a long man leaves one spot remaining. Kranick, who has a 1.59 ERA in seven exhibition appearances, deserves it.

Mendoza recently called Garrett, Butto and Young into his office to tell them they made the team. They weren’t exactly on the bubble, but he wanted them to know anyway. This will be the first Opening Day in the majors for Young and Butto.

“That means a lot,” Mendoza said.