Clowe played one shift after he was boarded by Capitals forward Jason Chimera 4:40 into the first period. Clowe played three shifts totaling 1:55 before leaving. The Rangers gave no details about the injury or his status for Game 6 on Sunday night.
Clowe missed the first three games of the series and the last game of the regular season with an undisclosed injury.
He played 12:19 and had an assist in Game 4 on Wednesday at Madison Square Garden.
The Capitals beat the Rangers 2-1 in overtime to take a 3-2 lead in the best-of-7 series.
Follow Dan Rosen on Twitter at: @drosennhl