Lock's practice performance will determine if he starts vs. Chargers

Denver Broncos head coach Vic Fangio has yet to determine a starting quarterback for Sunday's game against the Los Angeles Chargers.

Fangio said he'll increase rookie passer Drew Lock's reps in practice this week, leaving it up to the second-round pick to determine whether he'll make his pro debut.

"(The team will) see how he does with that and then make a decision prior to the game," Fangio said Wednesday.

Lock has been brought along slowly since returning to practice two weeks ago after undergoing thumb surgery in the preseason.

"Just feel like he's had a couple of good weeks of limited practices. I think he's ready to advance in his reps, and let's see where he's at further," Fangio said.

Third-year pro Brandon Allen has started the past three games and has led the team to a 1-2 record in that time. He threw for just 82 yards and an interception in a Week 12 loss to the Buffalo Bills.