The Miami Dolphins fear Ryan Tannehill will need season-ending surgery on his knee.

As second and third opinions await, Tannehill still could decide to rest it for six to eight weeks and try to come back from his knee injury again.

"He's done, I think," one source predicted Thursday night.

One source said Thursday that, because Tannehill did not repair his partially torn ACL during the offseason, his knee was "a ticking time bomb that was going to go off at any time."

The Dolphins have Matt Moore as Tannehill's backup and could also consider Jay Cutler and Colin Kaepernick.