Matt Bryant converted the 24-yard field goal for the 3-0 lead.
New England punted on its first possession, as did Atlanta on its second.
When the Patriots got the ball back, they ran the ball on 10 straight snaps and had great success despite the Falcons coming in as the fifth-ranked defense against the run in the league.
The drive began with a screen pass to Stevan Ridley, his second catch of the season, that he took for 24 yards.
Then alternating between Ridley, Blount, and Brandon Bolden (who left the game later in the second quarter with a knee injury), the Patriots picked up 50 yards on the ground, including a 14-yard run by Ridley through a big hole in the middle of the Falcons’ defense, helped in part by fullback James Develin.
On first and goal from the 3, it looked like Bolden scored, pushing linebacker Joplo Bartu back and diving for the goal line, but on review it was overturned, as Bolden’s knee was down before the ball crossed the plane of the goal line.
Ridley got the ball on second down and was stuffed for no gain, and on third down, perhaps the most unexpected of receivers, Matthew Mulligan, pulled in the touchdown.
Atlanta gambled on fourth and 2 when it got the ball back, passing up a short field goal to try to get a touchdown. White was open near the left sideline, but Ryan’s throw was off.
Rookie Kenbrell Thompkins, who had a drop earlier, made an impressive 49-yard grab over safety William Moore, the tail end of a fake-handoff, fake-reverse play that was the highlight of New England’s next possession.
Stephen Gostkowski tucked a 48-yard field goal try just inside the right upright for a 10-3 Patriots lead.
The Patriots took a 20-10 lead just 34 seconds into the fourth quarter, after a 47-yard run by Blount.
Right guard Dan Connolly pulled left at the snap, and helped open up a large hole for Blount, who picked up steam once he got to the second level and could not be caught.
It was the first rushing touchdown of the season for New England.
A play earlier, the Patriots converted on third and 19, with Brady hitting Thompkins with a 26-yard gain over the middle; Thompkins took a hit from Moore at the end of the play, and the safety was flagged for a personal foul, giving New England 15 more yards.
The Patriots got a 22-yard field goal from Gostkowski in the third quarter to take a 13-10 lead. But on the play preceding the kick, receiver Aaron Dobson was injured, held in the end zone and then crushed by two Falcons defenders.
Dobson was clutching his right shoulder area, but the team announced that he had a head injury.