BUFFALO — Johnny Boychuk raced off the ice with 4:33 to play Thursday night, holding his left shoulder. “That was ugly,” Travis Hamonic said of seeing his teammate hit the end boards at full speed after Boychuk got tangled up with Jack Eichel.

Jack Capuano said after the Islanders’ 2-1 win that Boychuk is day-to-day with an upper-body injury that is not a head or neck injury. “Luckily he’s OK,” Capuano said.

Boychuk still managed to do his usual night’s work, with 4:16 of penalty-kill time, a couple of blocked shots and 11 shot attempts. But in a one-goal game, Boychuk would have rotated with Hamonic every other shift during the last 4:33, and the Islanders had to muddle through with only five defensemen.

“Fortunately for us, Johnny skated off on his own and he’s only day-to-day,” Capuano said.

The Islanders still might need a defensive reinforcement from Bridgeport if Boychuk can’t play Saturday in Pittsburgh. Brian Strait was a healthy scratch, but Marek Zidlicky hasn’t played many back-to-backs and the Isles will host the high-flying Stars on Sunday.

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Halak rejoins team

Goaltender Jaroslav Halak flew up and skated with the extra players in the morning. Halak has been out with an upper-body injury since the holiday break ended on Saturday.

“He’s ready to be back with us, so that’s a good sign,” Capuano said. “He’s feeling better, he took some shots on the ice today. Any time that happens, you’re not far off.”

Christopher Gibson again backed up Thomas Greiss, who likely will get the call in Pittsburgh if Halak indeed is ready to return. If Halak isn’t ready, Gibson likely will make his NHL debut against the Penguins, with Greiss saved for Sunday’s game against the Stars.