U.S. forwards Jeremy Morin and Brock Nelson have undisclosed injuries and have been ruled out for Tuesday's game against Slovakia at the junior hockey world championships.
Morin is a top attacking threat and one of the eight returning players from last year's gold medal-winning team. He had a goal disallowed in a 3-2 overtime, tournament-opening win over Finland on Sunday.
Morin made his NHL debut this season with Chicago. He has two goals and an assist in nine games.
Nelson was hurt late in the third period Sunday. He was selected 30th overall by the New York Islanders in last summer's NHL draft.