Vancouver Canucks left wing Daniel Sedin left Wednesday's game against the Chicago Blackhawks in the first period.
Sedin exited the contest shortly after he was elbowed in the head by Blackhawks defenseman Duncan Keith.
Although he played on a subsequent power play, Sedin did not return to the game. Earlier in the period, Sedin had hit Keith in the head with his shoulder.
According to one account, Canucks center Henrik Sedin - Daniel's twin brother - said he heard Keith threaten retaliation on Daniel for the earlier hit.
Asked about a possible threat, Henrik said after the game: "You have to ask Keith. He's a tough Canadian guy so I am sure he is going to be honest."
Keith, who received a two-minute penalty for elbowing on the play, denied any attempt to injury Daniel Sedin.
"I'm not trying to hurt anybody," Keith said. "I hope he's OK."