Ovechkin crushed Fast into the boards, but the forward made it to the bench. After sitting in obvious pain for a few minutes, he went to the locker room.
Fast has five goals and 15 assists in 59 games.
Rangers coach Alain Vigneault also said that forward Michael Grabner left practice on Tuesday with a hip injury and is "up in the air" for New York's game against the Bruins on Thursday.
The coach said he is hopeful that defenseman Kevin Klein, who has been sidelined by back spasms, can stake Thursday in Boston.
Forward Mika Zibanejad was a late scratch Tuesday with an apparent hand injury, but Vigneault said Wednesday that he skated well during practice.