Queensland prop Nate Myles is under an injury cloud ahead of State of Origin II due to a knee complaint.

Manly co-captain Myles suffered the injury early on in the Sea Eagles' NRL loss to Penrith on Sunday.

Nate Myles is a key piece of the Maroons forward pack. Credit:Getty Images

Myles completed the match, but Manly coach Trent Barrett said the injury could spell trouble and the veteran forward has been sent for scans.

"He needs a scan on his knee, I don't know how serious it is," Barrett said.