FILE – In this Aug. 1, 2019, file photo, Denver Broncos quarterback Drew Lock scrambles during the second half of the Pro Football Hall of Fame NFL preseason game against the Atlanta Falcons in Canton, Ohio. The Broncos are bringing rookie quarterback Lock back to practice Tuesday, Nov. 12, 2019, to see if he is going to be able to play this season. (AP Photo/David Richard, File)

ENGLEWOOD | The Denver Broncos are bringing rookie quarterback Drew Lock back to practice Tuesday to see if he’s going to be able to play this season.

The second-round draft pick from Missouri went on IR to start the season after spraining his right thumb in an Aug. 19 preseason game against San Francisco.

His return will start a 21-day clock in which the Broncos (3-6) must decide whether to put him on the active roster or send him back to IR, ending his season and delaying his evaluation until 2020.

It’s that three-week window that prevented coach Vic Fangio from bringing Lock off IR two weeks ago when Joe Flacco (neck) went on IR and 27-year-old waiver wire claim Brandon Allen led Denver past Cleveland 24-19 in his first NFL start.

Fangio didn’t want the 21-day clock ticking on Lock during the Broncos’ Week 10 bye, so he waited until this week to bring him back.