The Detroit Lions had the worst defense in franchise history last season. If Dan Campbell’s first game as head coach is any indication, that mark won’t stand for long.
The San Francisco 49ers scored touchdowns on three straight possessions in the first half and added a fourth score on a 39-yard interception return by Dre Greenlaw as they steamrolled the Lions in Campbell’s debut as head coach, 41-33, at Ford Field.
Campbell joins Matt Patricia, Jim Schwartz and Marty Mornhinweg as Lions coaches to lose their first game with the franchise in the past 20 years.
Trailing 41-17 late in the fourth quarter, the Lions made a stunning 16-point comeback with short touchdowns — and two successful two-point conversions — from Jamaal Williams and Quintez Cephus sandwiching an onside kick recovery.
Trey Flowers then forced a fumble from 49ers receiver Deebo Samuel with 52 seconds to play recovered by rookie safety Ifeatu Melifonwu, giving the Lions an improbable last-gasp drive.
But Jared Goff threw incomplete on fourth down from the 49ers’ 24-yard-line to end the game.
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The 49ers averaged nearly 9 yards per play Sunday, passing and running at will the first three quarters against a defense that allowed the most points and yards in the NFL last season.
The Lions squandered scoring chances on their first two possessions. Jamaal Williams was stopped for a 1-yard loss on fourth-and-1 at the San Francisco 35 on the game’s opening drive, and Austin Seibert missed a 51-yard field seven plays later, after Jimmy Garoppolo fumbled the opening snap for the 49ers.
Garoppolo completed eight straight passes after his fumble as the 49ers built a comfortable 31-10 lead at halftime.
Rookie Trey Lance, the No. 3 pick of the draft, opened the scoring with a 5-yard touchdown pass to Trent Sherfield, and backup running backs Elijah Mitchell and JaMycal Hasty ran for touchdowns of 38 and 3 yards in the first half after starter Raheem Mostert left with a knee injury.
The 49ers rolled up 232 yards of offense on 25 plays in the first half, and added to their lead early in the third quarter when second-year cornerback Jeff Okudah got beat for a 79-yard touchdown pass by Samuel.
Okudah, who struggled as the No. 3 overall pick last season, had good coverage on Samuel, but failed to adjust to an underthrown ball and tripped after Samuel made the catch.
Okudah suffered a foot injury in the fourth quarter and went to the locker room.
As helpless as the Lions looked on defense, they weren’t much better on offense.
Jamaal Williams keyed an effective rushing attack with 53 yards on eight carries, D’Andre Swift scored on a 43-yard screen pass from Goff and T.J. Hockenson had seven catches for 81 yards and a touchdown.
But Goff, acquired in the offseason trade of longtime Lions starter Matthew Stafford, was ineffective in his Lions debut.
He tried forcing a pass to Hockenson into triple coverage on his interception, and misfired several passes to his overmatched receiving corps.
Goff completed three passes to Lions receivers in the first three quarters, two to Tyrell Williams and one to Amon-Ra St. Brown, and finished 31 of 45 passing for 244 yards.
Garoppolo was 16 of 24 passing for 303 yards, Samuel had eight catches for 178 yards and a touchdown, and Mitchell ran for 102 yards on 17 carries.
Contact Dave Birkett at dbirkett@freepress.com. Follow him on Twitter @davebirkett.