Two days before the start of their regular season, the Penguins finalized their 23-man roster Tuesday.

Twenty are players who skated for Pittsburgh last year, along with new forwards Alex Galchenyuk (acquired from Arizona in the Phil Kessel trade), Dominik Kahun (acquired from Chicago in the Olli Maatta trade) and Brandon Tanev (signed for six years/$21M in free agency).

There’s been a swap at the backup goalie position, where Tristan Jarry will start the season with the big club over Casey DeSmith, who cleared waivers Tuesday and was assigned to the AHL Wilkes-Barre/Scranton Penguins.

With other factors in their preseason performance being about equal, the decision came down to $330,000 – the approximate amount the Penguins were over the NHL salary cap, and something that could be remedied by choosing Jarry’s $675,000 contract over DeSmith’s $1.25M.

“I think it’s obvious the business of the game is part of the decision-making process,” head coach Mike Sullivan said. “It’s just the reality of the situation that we’re in right now. We have three really, really good goalies and these are very, very difficult decisions. None of us take them lightly.

“We’re thrilled that Casey cleared. We think it’s great for us because we want him to be a Pittsburgh Penguin.”

For Jarry, meanwhile, it’s a big opportunity.

“It’s my first time ever making the team out of camp, so it’s pretty exciting for me,” said the 24-year-old, former second-round draft pick. “I think I kept improving every year, and going down to Wilkes last year with the motivation to be back – it’s always hard to be in the NHL and leave and have to work your way back, so I just had to keep developing and keep pushing myself. It’s every kid’s dream to be in the NHL and be a full-time player in the league.”

Cap relief via LTIR

As it turned out, the Penguins didn’t even need the goalie move to get cap compliant – for the time being, at least. An injury to forward Bryan Rust, sustained in their preseason finale Saturday when a shot hit his left hand, took care of that as he’ll head to long-term injured reserve.

Captain Sidney Crosby, who left earlier in the same game after taking a shot off his foot, had better luck. He’s back to practice and seems likely to play in the season opener.

Galchenyuk, meanwhile, who’s shown preseason chemistry alongside center Evgeni Malkin, is day-to-day with a nagging lower-body injury.

“It would’ve been nice to try to keep everybody healthy to get through [the preseason], but that didn’t happen,” Crosby said. “But you find a way, and I think our mentality is in the right spot going into game one.”

Familiar looks on D

Beleaguered defenseman Jack Johnson has spent much of the preseason looking like a very expensive seventh D, as sophomore Juuso Riikola found himself alongside Erik Gudbranson on the Penguins’ third pairing.

After a report that Johnson could be on the move this week, in a move that could free up to $3.25M over the next four years, depending on retained salary, he was back in a top-four role at Tuesday’s practice alongside Justin Schultz, where he played much of last season.

What does that mean for the opener? Sullivan wasn’t tipping his hand.

“I think we have an idea of what we want to do, the options,” the head coach said. “Some of the looks you saw today were familiar looks from last season, but I think we have an idea of what we want to do.”