Blount, Gostkowski give Patriots 10-point lead
Blount ran through the middle of the line of scrimmage and outraced safety William Moore and cornerback Desmond Trufant down the left sideline for the score.
The Patriots had gone ahead 13-10 with 5:29 left in the third on Stephen Gostkowski's 22-yard field goal.
Patriots quarterback Tom Brady was 9 of 14 passing for 83 yards in the third, but he lost another receiving target on the snap that preceded Gostkowski's score.
Receiver Aaron Dobson was injured in the end zone while attempting to catch a touchdown pass.
Falcons cornerback Robert Alford appeared to hold Dobson on the route, and Brady threw the ball into the artificial turf in front of both players.
Atlanta safety Thomas DeCoud knocked his knee against the front of Dobson's helmet as Dobson fell to the turf. Dobson was on his back for a couple of minutes before New England's medical staff attended to him.
Dobson walked off the field under his own power, but was questionable to return.
Brady's 1-yard touchdown pass to Matthew Mulligan and Gostkowski's 48-yard field goal gave New England a 10-3 lead earlier in the second quarter.
Gonzalez was open on the right sideline after linebacker Dont'a Hightower bumped him in coverage and let the 13-time Pro Bowl tight end catch the pass easily and beat safety Steve Gregory to the right goal line marker.
Matt Bryant kicked a 23-yard field goal to give the Falcons a 3-0 lead on the opening drive.
The 13-play, 75-yard drive stalled at the 6 when Ryan overthrew Gonzalez and Julio Jones in the end zone.
New England's first drive ended when Kenbrell Thompkins dropped a pass that would've been a first down, and the Patriots had to punt.
Stevan Ridley energized New England's offense late in the first, catching a 24-yard pass and running three times for 26 yards to help set up Mulligan's TD catch that gave the Patriots a 10-3 lead early in the second.
Atlanta, which began the game with a 1-2 record, failed to convert a fourth-and-2 from the New England 7 midway through the second when Ryan threw behind Roddy White near the left sideline.
New England, off to its best start in six years, was trying to improve to 4-0 and tie Denver and Kansas City for the AFC's best record.
The Patriots had yet to face a quarterback this season as successful as Ryan. Others were rookies EJ Manuel of Buffalo and Geno Smith of the New York Jets and Josh Freeman of winless Tampa Bay.
New England's defense had allowed just three touchdowns this year, but the Patriots' offense has only four touchdowns in 13 trips inside the opponents' 20-yard line for an NFL-worst 69.2 percent through three games.
Atlanta entered the game with a 34-7 record under coach Mike Smith at the Georgia Dome, but his defense looked confused on a 49-yard pass from Brady to Thompkins that set up Gostkowski's field goal.
Brady faked to Julian Edelman on a reverse and connected with Thompkins, who jumped to beat strong safety William Moore for the big gain.
Brady attempted just nine passes in the first half, completing five for 96 yards, but he has thrown a TD pass in 52 consecutive games, the NFL's second-longest career - and active - streak behind Drew Brees' 54 straight for New Orleans.
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