WATFORD, England (AP) -- Minnesota Vikings quarterback Christian Ponder is questionable for Sunday's NFL game in London against the Pittsburgh Steelers because of a rib injury.
Vikings coach Leslie Frazier says Wednesday's practice will "be a big signal in what direction we'll have to go."
Backup quarterback Matt Cassell is ready to step in if Ponder is ruled out.
Ponder says "we're going to push it to the limit and see what we can do, in a smart way. But I'm doing everything I can to play."
Ponder, who has thrown five interceptions and two touchdowns for a 65.9 passing rating, says he picked up the injury early in Sunday's 31-27 loss to the Cleveland Browns, which dropped Minnesota to 0-3.
The Steelers are also 0-3.