West Coast fear another significant knee injury for star AFL ruckman Nic Naitanui.

It will be a massive blow for the Eagles’ top-four hopes if Naitanui is sidelined.

The 2012 All-Australian left the field during the second term of Sunday’s clash with Collingwood at the MCG and went straight to the rooms.

He has a right knee injury and coach Adam Simpson confirmed at halftime that Naitanui is out of the match.

Naitanui hurt his knee in a marking contest on the wing and was seen limping heavily in the Eagles rooms afterwards.

Sunday was Naitanui’s 15th AFL match this season after returning from a left knee reconstruction.

“It doesn’t look great for his other knee. We’ll worry about that after the game,” Simpson told Fox Footy.