On Detroit's final drive, a pass-interference penalty against Atlanta was overturned because instant replay showed defensive tackle Corey Peters had tipped the ball. Lions quarterback Matthew Stafford appeared to injure his right ankle on the play.
He then throw incomplete on fourth down from the Atlanta 41 and limped off the field.
The Falcons (4-3) ran out the clock with a first down to win consecutive games for the first time this year.
The Lions (5-2) have lost two straight after their perfect start.
Ryan's 17-yard pass to Roddy White put Atlanta ahead 17-6 at halftime.
Calvin Johnson caught his 10th touchdown pass late in the third quarter to pull Detroit within four points.