The Bucs have downgraded Wirfs (knee) to doubtful for Sunday's game against the Giants, Tom Pelissero of NFL Network reports.
Wirfs is recovering from a sprained MCL, which he suffered in the Bucs' pre-bye Week 10 loss to San Francisco. He was initially listed as questionable on Friday's injury report. Justin Skule figures to be the next man up at left tackle if Wirfs misses Sunday's contest.