Kyle Palmieri suffered a torn ACL in his left knee on Friday and will miss the rest of the season, the Islanders said on Saturday.
Palmieri will undergo surgery on his knee, with a timeline to return of six to eighth months.
The news comes as a devastating blow to the Islanders, for whom Palmieri was a crucial piece of the top six.
He was also one of their most durable players over the last few seasons, playing 223 consecutive games, 90 more than any other Islander.
That streak will end Sunday against the Capitals.
Max Shabanov and Mathew Barzal both missed Saturday's practice due to maintenance — both are expected to play Sunday — but it is expected that Shabanov will play on the second line with Bo Horvat and Emil Heineman , on Sunday, the same way the Islanders finished Friday's game.
Maxim Tsyplakov is expected to come back into the lineup on the fourth line, and Marc Gatcomb would be a likely call-up from AHL Bridgeport as an extra.
Palmieri was quietly in the middle of a strong season after signing a two-year, $9.5 million extension during the offseason, with six goals and 12 assists over 25 games.
Islanders center Kyle Palmieri (21) falls to the ice after an injury against the Philadelphia Flyers during the second period at UBS Arena. IMAGN IMAGES via Reuters Connect
His injury adds a second major piece the Islanders have lost for the season in the span of just over a week, with Alexander Romanov requiring shoulder surgery following a hit from Mikko Rantanen at the end of the Islanders' win in Dallas last Tuesday.
Jean-Gabriel Pageau is also out with an upper-body injury, but expected back before Christmas.
Palmieri's injury did not come as the result of anything dirty; rather, he appeared to fall awkwardly during a routine battle with Jamie Drysdale while skating into the corner.
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The Islanders will have some added cap flexibility if and when Palmieri's $4.75 million salary is added to long-term injured reserve, but that is largely academic.
Though Pierre Engvall is currently their only player on LTIR, adding Romanov ($6.5 million) and Semyon Varlamov ($2.75 million) can happen whenever the Islanders have need of the extra room, so the Islanders are not really in need of more LTIR space.
The pair of season-long injuries significantly changes the picture for the Islanders after a successful first 25 games of the year.
For the time being, general manager Mathieu Darche's likely course of action will be to wait and see whether his team can stay in the hunt while banged up.
If the Islanders can hang around, then it wouldn't be surprising to see them try and make a run at Vancouver winger Kiefer Sherwood , who is known to be available via trade and whose contract expires at the end of the season.
Nevertheless, there is no reason to rush into a trade that would require the Islanders to give up major assets before they know whether or not this group can survive the losses of Palmieri and Romanov.
If it turns out they can't, the Islanders could parlay their LTIR space to act as a banker at the trade deadline and potentially net draft picks in exchange for taking on an extra contract.
Pageau and Anders Lee , who are on expiring contracts, would likely fetch high prices on the trade market if the Islanders decided to be full-blown sellers.
That decision will, ultimately, be dictated by the roster of players that just took a body blow.
