The Redskins lost rookie quarterback Robert Griffin III during Sunday's loss to the Atlanta Falcons. (US Presswire)

It was inevitable and it finally happened. Washington Redskins QB Robert Griffin III ran around left and instead of running out of bounds or throwing the ball away, he opted for a slide. And just as he went into his slide, linebacker Sean Weatherspoon went into him -- and drilled him.

That knocked Griffin from Sunday's game and, for the first time this season, gave the Redskins a glimpse of a rookie quarterback with a lot to learn in Kirk Cousins. Though Cousins managed a 77-yard touchdown pass to Santana Moss for a brief three-point lead, he also threw two interceptions on the final two possessions.

So it’s no surprise that the Redskins (2-3) ended up losing to the Atlanta Falcons, 24-17. The Falcons are now 5-0 for the first time in franchise history, and they are one of only two undefeated teams in the NFL, the other being the Houston Texans, who are 4-0 and play Monday night against the Jets.

Without Griffin, everything changes for the Redskins. Even with him Sunday, it was a struggle. He only had 91 yards passing when he exited in the third quarter.

Griffin never carried the ball on a designed run Sunday, and he was listed with only one carry for seven yards off a bootleg. On the play in which he was hurt, the Redskins faced third-and-goal from the 3-yard line when he ran out of the pocket to the right.

“Robert is going to keep on learning,” coach Mike Shanahan said. “But we have something very special. We’ve got a guy that competes and tries to make plays. Every game he goes in, just like that last play in the red zone… that’s part of the learning experience.”

Aside from the 77-yard touchdown pass, the Redskins managed only 34 yards and one first down when Griffin was out. Their zone read game sets up running back Alfred Morris with good holes by freezing linebackers, but without that the running game was stopped.

“That’s why we have other guys,” Redskins receiver Santana Moss said. “We just have to be ready for situations like that.”

When the game turned: The Redskins took a 17-14 lead with 12:34 left, but the Falcons responded with a nine-play, 45-yard drive that they capped with a 53-yard Matt Bryant field goal. But this was only the beginning. After a three-and-out by the Redskins, the Falcons drove 69 yards in six plays for a 13-yard Michael Turner touchdown and 24-17 lead.

Highlight moments:
  • Redskins linebacker Ryan Kerrigan took care of the point production in the first half when he made a terrific read and an even better play. Kerrigan rushed upfield and read Matt Ryan wanting to throw a swing pass to the running back in the right flat. Kerrigan played for that, timed his jump, intercepted the ball and ran 28 yards for the games first score in the second quarter.

  • Rookie quarterback Kirk Cousins connected with receiver Santana Moss for a 77-yard touchdown in the fourth quarter. Moss was wide open, splitting the safeties – neither of whom ran with him. It was Cousins’ first career scoring pass.

  • Ryan connected with receiver Julio Jones on an 18-yard pass along the sidelines in the end zone. Jones beat a cover-2 defense with the safety, Reed Doughty, late coming over. Jones caught the ball over corner Josh Wilson and tapped both feet in bounds for the successful catch.

  • This was a highlight for the Falcons: corner Dunta Robinson broke off his man in the flat and jumped a pass to tight end Fred Davis for an interception late in the fourth quarter. Safety Thomas DeCoud made an interception with 1:05 left, clinching the win.
Top-shelf performances:
  • Running back Alfred Morris gained 115 yards on 18 carries, with a long of 29. Morris had five carries of at least 12 yards. The line blocked well for him, and Morris continues to help himself with his ability to press the hole.

  • Falcons receiver Tony Gonzalez caught 13 of the 14 passes thrown his way for 123 yards, and time and again served as a great target for quarterback Matt Ryan. Gonzalez caught a 21-yard touchdown pass.

  • Receiver Julio Jones also had a huge day, with 10 catches on 15 passes thrown to him for 94 yards and an 18-yard score. Jones caught just one of eight passes thrown to him a week ago.

  • Ryan completed 34 of 52 passes for 345 yards and two touchdowns. He was intercepted once. Ryan came through in the fourth quarter, completing seven of nine passes for 77 yards and a touchdown.
What they said about Kirk Cousins interceptions:
  • Cousins: “They were dropping off, playing soft. When they do that, you have to come underneath. I wanted so badly to take us down, and I wanted to do too much and a couple throws got away from me. In hindsight, take a 3 or 4-yard gain and be patient and let it come to me. I tried to do too much.”
What they said about Billy Cundiff’s missed 31-yarder:
  • Cundiff: “I just missed a kick. I don’t think there’s any reason to go into extreme detail. I just missed. It’s a kick I should make. It’s a very makeable kick. It just didn’t happen.”
What they said about Tony Gonzalez:
  • Ryan: “I’m just constantly impressed by how consistent and how talented he is and for him to be in year whatever it is and playing at the level he is -- I’m just really impressed. His moves have gotten better too since last year. He made a lot of guys miss on the field today.”

  • Falcons coach Mike Smith on Gonzalez: “Phenomenal. The guy just amazes me every time he goes out there on the field. He’s just an unbelievable tight end, in my mind the greatest that ever played.”
What they said about Ryan Kerrigan’s touchdown:
  • Kerrigan: “I saw the tackle give me a little free ride, like most tackles do when it’s a screen pass. And I saw the back scatting, and I tried to trail him a little bit. Fortunately, I was right in the throwing lane, and I was able to make the play.”
Numbers you should know:
  • The Redskins have lost eight straight games at home. They haven’t won at FedEx Field since Sept. 18, 2011 over Arizona.

  • Redskins receiver Santana Moss now has 500 career catches, making him the fourth player in franchise history to achieve that amount. He joins Art Monk, Gary Clark and Charley Taylor.

Injury update: Robert Griffin III suffered a mild concussion and will be re-evaluated Monday. Griffin later tweeted that he thinks he’ll be cleared and able to play next week vs. Minnesota.

Going forward: The 2-3 Redskins just started one of the toughest parts of their schedule with improving Minnesota at home next week followed by road games at the New York Giants and Pittsburgh Steelers. The same thing was said before the Tampa Bay game, but the Redskins need a win to avoid another slide.

The Falcons host the Raiders followed by a game at Philadelphia and a home game against the Cowboys. They don’t appear to be a team ready to slow down any time soon.

John Keim covers the Redskins for the Washington Examiner. Follow him on Twitter @CBSRedskins or @John_Keim