Jared Goff threw only his second touchdown pass in the first quarter this season.
Amon-Ra St. Brown scored on a 27-yard reception, giving the Lions a 7-0 lead with 11:59 remaining in the first quarter.
The Lions took the opening kickoff and went 69 yards in six plays.
The big play came on the second play when Goff hit Jahmyr Gibbs, who raced 30 yards to the Tampa Bay 39 before Tykee Smith pushed Gibbs out of bounds.
Goff was 2-of-3 for 57 yards and a touchdown, and Gibbs had two carries for 3 yards.