Patrick Roy's lineup decisions will be key for Islanders as they host Rangers on Tuesday

Patrick Roy has no margin for error when it comes to formulating his lineup for the Islanders’ crucial game against the Rangers on Tuesday night at UBS Arena. The coach’s decisions must be on point to give the Islanders every advantage with their playoff hopes quite possibly in the balance.

And there are options for how he constructs his forward lines and defensive pairs, especially with top-four defenseman Noah Dobson eligible to be activated off long-term injured reserve after missing 10 games across five weeks with a lower-body injury.

The Islanders, who knocked off the rust from a two-week hiatus for the NHL’s 4 Nations Face-Off tournament with a 4-3 loss to the visiting Stars on Sunday night and have lost three straight, sit three points behind the Rangers (albeit with a game in hand) in the Eastern Conference standings. The Islanders also are five points behind the Senators for the second wild-card spot, again with a game in hand.

The difference between potentially earning or ceding two points against the Rangers is seismic.

The decision on defense may have been made on Monday when Islanders president/general manager Lou Lamoriello did not place any player on waivers, which would have been one way to clear a roster spot for Dobson. The Islanders still could move a player to injured reserve to open a spot while moving Mathew Barzal (lower body) from injured reserve to LTIR to create salary-cap space for Dobson.

Presumably, Dobson’s return would come at the expense of Scott Perunovich and give the Islanders four righthanders among their six defensemen, including Ryan Pulock, Scott Mayfield and Tony DeAngelo, meaning one would play on his off-side. Or Roy could sit DeAngelo to keep the lefthanded Perunovich in the lineup to give him three lefty-righty pairs.

“It’s hard to speculate right now,” Roy said. “We’ll deal with it. If we have four right, we’ll have four right. The urgency for our team is to find a way to win hockey games.”

Roy started blending his forward lines against the Stars even before Casey Cizikas was ejected for a questionable match penalty — the play drew no supplemental NHL discipline — in the second period. Notably, he moved Simon Holmstrom from Jean-Gabriel Pageau’s third line to Brock Nelson’s second line with Kyle Palmieri instead of Maxim Tsyplakov. That trio was on the ice for Palmieri’s tying goal in the second period.

Holmstrom, with five goals and three assists in his last 11 games, has grown confident in his shot and has been one of the Islanders’ most consistent forwards.

“He’s playing so well, it’s fun to watch,” Roy said. “Honestly, he deserved to be where he is. It’s a luxury to see a guy like this playing the way he’s been playing.”

Meanwhile, Anthony Duclair notched his first goal (and point) in eight games on Sunday, likely keeping him on Bo Horvat’s top line with Anders Lee for the time being.

“A little better,” said Duclair, who had four shots against Dallas and has five goals and four assists in 26 games. “Opportunities, but still not enough. I think there’s still another level I can get to, for sure.”

Decisions, decisions.

By Andrew Gross

andrew.gross@newsday.comAGrossNewsday

Andrew Gross joined Newsday in 2018 to cover the Islanders. He began reporting on the NHL in 2003 and has previously covered the Rangers and Devils. Other assignments have included the Jets, St. John’s and MLB.