Russell Wilson suffered an MCL spain in Sunday's win over the San Francisco 49ers, according to a source.
He was scheduled for an MRI on Sunday night.
"I don't think it's severe as it looked," Wilson said after the game. "I have good mobility. ... You always feel better when you win."
Wilson departed in the third quarter after linebacker Eli Harold took him down on a sack. He briefly returned, but was replaced by rookie Trevone Boykin soon after.
"He's in good spirits, just like you would think," Pete Carroll said. "He has no intention of thinking anything other than that he's playing."
The Seahawks will travel to New Jersey to play the New York Jets on Sunday.