UPDATE, 2:56 PM: Grabner's injury is being described as an "upper body injury." Both he and Cal Clutterbuck will be out against the Sabres on Sunday.
Calvin de Haan, who was cut on the forehead by a skate blade on Saturday, will also miss the game in Buffalo. Lubomir Visnovsky will suit up in his place.
Colin McDonald and Harry Zolnierczyk have been emergency recalled from Bridgeport and will play on Sunday.
Zolnierczyk has 14 goals and 22 assists in 47 games for Bridgeport this season. He appeared in 13 games for the Penguins last year and scored two goals.
It's interesting that Grabner is the one that ends up on IR, considering Cal Clutterbuck and Calvin de Haan both left the game with injuries on Saturday and did not return. Losing Grabner will not help that embattled penalty kill, which surrendered a goal in the first, but was successful in two out of three attempts in Boston. With the last place PK in the league, the Islanders need to get it straightened out in a hurry, and they'll have to lean on guys like Frans Nielson, Nikolay Kulemin, and Clutterbuck in Grabs' absence.