Vikings head coach Leslie Frazier confirmed on Wednesday that Ponder has not participated in practice so far this week due to injured ribs. Ponder suffered the injury during Week 3's loss to the Browns. Cassel has been solid in practice this week, according to Fraizer.
Cassel's former teammate, Patriots quarterback Tom Brady, acknowledged to CBS's Jason La Confora that his former backup could start in the game at Wimbley Stadium in London. Brady broke the news after being asked about the success of his former backups in the NFL. "The backup quarterback, there's only been two of us, Brian [Hoyer] and I at one time and now myself and Ryan Mallett," said Brady. "We have a great rapport. I'm friends with all those guys. Matt Cassel, I talk to -- he may be starting this weekend."
The Vikings and Steelers will face each other at Wimbley Stadium in London on Sunday at 1 p.m. ET on CBS.