Denver Broncos to start rookie QB Drew Lock vs. Los Angeles Chargers

Dec. 1 (UPI) -- The Denver Broncos will turn to rookie quarterback Drew Lock for Sunday's game against the Los Angeles Chargers.

League sources told ESPN and NFL Media on Sunday that Lock will make his first NFL start against the Chargers. He will become the third starting quarterback for the Broncos this season after Joe Flacco was placed on injured reserve and Brandon Allen's benching.

Lock, the 42nd overall pick in the 2019 NFL Draft out of Missouri, was on injured reserve since the beginning of the regular season due to a thumb injury. He sustained the injury in the preseason and hadn't practiced since August before returning to the practice field in mid-November.

The Broncos officially activated Lock off injured reserve Saturday and waived quarterback Brett Rypien in a corresponding roster move. Rypien was on the team's roster throughout the off-season program, training camp and regular season.

Denver's offensive unit has struggled to this point in the season, scoring over 16 points only four times in 2019. The Broncos (3-8) are ranked 28th in the league in scoring and 27th in total offense.

The Broncos will host the Chargers (4-7) at 4:25 p.m. EST on Sunday in Denver.