In a game that had the makings of a shootout between two of the NFL’s hottest quarterbacks, the Atlanta Falcons’ Matt Ryan was largely ineffective until late in the game and the Washington Redskins lost rookie star Robert Griffin III to a third-quarter concussion.

Ryan, who entered the game with the best passer rating in the league, managed to shake off his struggles and lead Atlanta to three fourth-quarter scoring drives. Rather than turning to Griffin — the NFL’s offensive rookie of the month for September — for late game heroics, Coach Mike Shanahan had to play rookie Kirk Cousins, who hadn’t taken a snap during the regular season. The comeback bid failed as Cousins threw two interceptions in the final two minutes, and Washington fell, 24-17.

The Falcons entered the fourth quarter trailing 10-7 but outscored the Redskins 17-7 in the final stanza and left FedEx Field as the only 5-0 team in the NFL (the 4-0 Houston Texans play Monday night). Washington fell to 2-3 and suffered its eighth consecutive home defeat.

The Redskins play at home again Sunday, but won’t find out until later this week whether they will host the Minnesota Vikings with Griffin in uniform.

Griffin was running wide when Atlanta linebacker Sean Weatherspoon’s shoulder slammed into the left side of Griffin’s helmet. In the minutes that followed, the quarterback didn’t know the score of the game or what quarter it was, Shanahan said.

“We knew he had a mild concussion, at least according to the doctors. It feels good right now, a lot better right now,” Shanahan said after the game. “But that was the situation and why he didn’t go back into the game.” Griffin was sent home, not to a hospital.

Both teams entered the game with a demonstrated ability to put points on the board. The Falcons ranked third in the NFL, averaging 31 per game and the Redskins were fourth at 30.8. But neither offense got in gear during the first quarter.

The Falcons managed only 70 yards on three possessions and never ventured across midfield. Washington, meanwhile, mustered only 30 yards and went 0 for 2 on two third down conversion attempts in the first quarter.

The Redskins got on the board first, but the points came from their defense. Linebacker Ryan Kerrigan leaped to snag a Ryan screen pass and rumbled 28 yards for a touchdown. It was the second interception and touchdown of Kerrigan’s career; as a rookie last season, he deflected and intercepted a pass in his first career game and scored against the New York Giants.

The play also marked Washington's third defensive touchdown this season. The last time the Redskins had at least three defensive touchdowns in one season was 1999, when they totaled four. But they have lost all three games when the defense scored.

“We definitely felt like we gave them too many chances,” cornerback DeAngelo Hall said. “We had an interception for a touchdown, but you would like more. I know it’s hard to say, but you want to keep asking for more. More from me, more from all the guys in this locker room.”

Atlanta center Todd McClure and Ryan botched a snap in the second quarter and Redskins inside linebacker Perry Riley recovered the ball at his team’s 32-yard line. The offense then had its best possession of the game, going 55 yards down to the Atlanta 13-yard line in five plays, highlighted by a 20-yard catch-and-run by running back Alfred Morris, followed by a 29-yard run by the rookie. But Washington squandered the opportunity.

With Washington denied on third down, kicker Billy Cundiff lined up for a 31-yard field goal and missed it wide right. That followed last week’s dismal performance by the kicker, who missed three field goals before hitting the game-winner against the Tampa Bay Buccaneers.

“It’d be much easier to keep it brief,” Cundiff said when asked what happened on his latest miss. “I don’t see any reason to go into extreme detail. It was just a miss. I think it’s a kick I should make. It was a makeable kick. I just didn’t hit it.

Cundiff’s miss appeared to suck the life out of the Redskins and their fans. Atlanta marched down field with an eight-play, 79-yard drive that took only 1 minute and 46 seconds and was capped by a one-yard touchdown pass to Tony Gonzalez in the right corner of the end zone. Gonzalez, in his 16th NFL season, finished the game with 13 catches for 123 yards.

The half ended in a 7-7 tie, though Atlanta held the ball for 19:55 of the 30 first-half minutes, and had 16 first downs and 221 total yards (187 of them passing). Washington had only seven first downs and 138 yards of offense (93 of them rushing).

The Redskins threatened to score late in the third quarter, but instead lost Griffin for the rest of the game with what the Redskins are calling a mild concussion.

With the Redskins facing third-and-goal from the Atlanta 3, Griffin took the snap and rolled to his right, looking for a receiver in the end zone. He tucked the ball and tried to turn the corner, but was drilled by Weatherspoon, whose right shoulder slammed into the left side of Griffin’s head. Griffin lay facedown along the far sideline, and had to be helped up. He was wobbly as he headed off the field.

Cundiff made a 23-yard field goal to give Washington a 10-7 lead with six minutes left in the quarter. But all eyes were on Griffin, who sat on the bench and appeared to be treated for a bloody lip, then was taken to an observation area beneath the stands behind Washington’s bench.

After several minutes, Griffin came out and walked slowly to the locker room with members of Washington’s training staff and team doctor Anthony Casolaro.

Cousins warmed up on the sideline and entered the game for a three-and-out series before the fourth quarter ended. He threw a four-yard completion to Josh Morgan on his first NFL pass attempt but threw an incompletion on third down. The Falcons went down the field following a punt and scored on an 18-yard pass to Julio Jones. But Washington struck quickly.

Facing third-and-nine from his own 23, Cousins completed a strike down the center of the field to a wide open Santana Moss, who raced downfield for a 77-yard touchdown.

But, playing from behind after a 13-yard touchdown run by Atlanta’s Michael Turner, Cousins threw two interceptions in the final two minutes, and Washington missed out on a chance to string together back-to-back victories for the first time since Week 2 of the 2011 season.