The Bombers say Willy's status is week-to-week but that he's questionable for Winnipeg's next game at home against the Hamilton Tiger-Cats.
"He will be re-evaluated at the beginning of next week," the team said in a brief statement Monday. The team didn't provide any more information about the nature of the injury.
Willy's throwing shoulder was injured on what looked like a hit from Alex Bazzie and Khreem Smith, as Willy was sacked late in the second quarter in their 25-9 loss to the B.C. Lions Saturday.
After the game, coach Mike O'Shea suggested the injury might not be serious, although Willy watched from the sidelines in the second half as backup Brian Brohm struggled against B.C.'s defence.
At 27, Willy has been remarkably durable, or lucky, as far as injuries are concerned, with only a hand injury in practice that made him miss two games during his college career and none that have forced him to miss a game as a professional.
This season he has hardly missed a snap let alone a game, despite hits that have left him bruised and limping off the field at times.
It helps that this is Winnipeg's bye week, which gives the team and Willy some time to recover or prepare. They don't have to play again until Sept. 27.
The Bombers aren't suffering alone.
Willy joins Darian Durant, Travis Lulay and Bo Levi Mitchell on the injured list. Like Willy, Mitchell went down Saturday, although in his case it was a leg injury, and also like Willy he hadn't missed a game this season.
B.C. has veteran Kevin Glenn, who has already played most of the season for Lulay, and Calgary has Drew Tate if Mitchell can't return. But the Bombers have the untested Brohm to back up Willy.
The Saskatchewan Roughriders have also been forced to go with rookie backup Tino Sunseri, who made his first CFL start Sunday, a 28-3 loss in Hamilton that gave the Tiger-Cats just their third win of the season.
With Durant out, Saskatchewan's hold on second place in the CFL West looked tenuous as they fell to an 8-3 tie with the Edmonton Eskimos after weekend games.
Mike Reilly, the last starter standing in the West, completed 22 of 32 throws Friday for 271 yards and ran for two touchdowns as the Eskimos put away the Montreal Alouettes 33-16.
Although the Bombers are in last place in the CFL West at 6-6, Willy has been the player who kept them in the game for much of this season. He leads the league in passing yards at 2,977, at least for now.
The Bombers went 5-1 to open the season, although most of their games were against eastern teams that have struggled against every team in the West. The Bombers then started to play more in their own division and have a 1-5 record since, with that one win against the Alouettes.