Lock (heel/left elbow) is listed as doubtful for Sunday's game versus the Ravens, Dan Salomone of the Giants' official site reports.
Lock emerged from this past Sunday's loss to the Saints with a heel injury that required a walking boot. As the week went on, coach Brian Daboll conceded that Tommy DeVito would start in place of Lock, but the latter still had a chance to be the emergency third quarterback Sunday, per Jordan Raanan of ESPN.com. Considering Lock now is doubtful to suit up, though, practice-squad member Tim Boyle will presumably be elevated to the active roster Saturday to serve as the backup.