Rangers captain Ryan McDonagh didn't practice Monday because of a hand injury and is unlikely to start when the series opens in Pittsburgh on Wednesday.
Coach Alain Vigneault expects Lundqvist and Girardi to practice Tuesday, but the Rangers face a tough task in the opening round against one of the NHL's hottest teams.
Without McDonagh the job will be even tougher. He skated before practice.
Vigneault described his status as day to day, later adding that he would not start.
Neither McDonagh nor Lundqvist were made available to reporters.
Forward Rick Nash said McDonagh can't be replaced.
"I don't think you can compensate to fill the boots of a guy like that," Nash said of McDonagh. "He is obviously our captain, our best player. It's going to give another guy a chance to step up. You have to look at the positives out of every situation."
Skjei is the likely choice because he is left-handed shot like McDonagh. That would keep fellow defenseman Dan Boyle from having to switch sides.
"Everyone in here still has the same goals, to win hockey games," forward Mats Zuccarello said of approaching the series without McDonagh. "With Ryan out, other people just have to step up and play well. I think we have good team regardless. He is a key player of our team, so everyone has to step up. We can't think about that."
Vigneault knows Lundqvist is ready.
"As you know, his will to win, you can't measure," the coach said. "He loves the game so much so. I think like the rest of our team he is looking forward to this challenge."
Girardi skated with McDonagh before practice, and he was supposed to skate again after it.
"If there is nothing that happened between now and tomorrow, he should practice with the team," Vigneault said.
Eric Staal, who left the season finale against Detroit with an upper-body injury, said he is fine.
"I am not worried about it," Staal said. "It was one of those freak little plays that scared me for a half second. We checked all the boxes we needed to after game, good day yesterday, and I felt fine today."
The Rangers have knocked the Penguins out of the playoffs the past two seasons.
"Just because you have had success in the past doesn't necessarily mean you'll have it going forward," forward Chris Kreider said. "We have to bring our best foot forward because although they have a different team from last year, and we have a different team, they have the same skill and the same speed, maybe even moreso."