John Harbaugh won his challenge, with Ravens running back Javorius Allen touching the pylon with the football before going out of bounds.
Allen’s 12-yard catch-and-run from Joe Flacco gave the Ravens a 17-14 lead.
Flacco is 13-for-18 for 134 yards and the touchdown.
The nine-play, 52-yard drive was highlighted by a 19-yard catch by Michael Crabtree, who has five receptions for 45 yards.
The Broncos have scored on runs of 6 yards by Royce Freeman and 35 yards by Emmanuel Sanders.
Alex Collins has a 6-yard touchdown run for the Ravens, and Justin Tucker has kicked a 52-yard field goal.