THERE are fears Michael Walters may spend some time on the sidelines after injuring his knee in the first quarter of the western derby on Sunday.

Walters was involved in a contest at half-forward which resulted in a Brandon Matera goal and came out of it with a significant limp.

The Dockers star came to the bench soon after, where medical staff looked at his left knee, which had already been strapped before the game.

Walters went to the rooms at the quarter-time break with club doctor Ken Withers.

He returned to the field briefly in the second term but could barely run.

The injury could be a significant blow for Fremantle, with Walters having already kicked a stunning goal on his right foot early against the Eagles to add to his nine goals in the opening five rounds.