Washington Redskins survive the loss of rookie QB Robert Griffin III and pull off a last-second comeback, keeping playoff hopes alive with flair. (The Washington Post)

Kirk Cousins has been the “other” rookie quarterback for the Washington Redskins all season, the understudy to a league most valuable player candidate and a growing pop-culture phenomenon, Robert Griffin III.

But it was Cousins, not Griffin, who made the plays that mattered most for the Redskins on Sunday, as they beat the Baltimore Ravens, 31-28, in overtime at FedEx Field to remain in the thick of the NFC playoff chase.

With Griffin in and out of the lineup on the Redskins’ final drive of regulation after injuring his right knee, Cousins threw an 11-yard touchdown pass to wide receiver Pierre Garcon, then ran for a tying two-point conversion on a quarterback draw with 29 seconds remaining to send the game into overtime.

“I have a lot to live up to if my number does get called because of the way he’s played. . . . He’s doing a tremendous job,” Cousins said of Griffin. “I’m trying to learn from him as I watch and stay locked into these games when I’m not playing.”

Cousins’s late-game exploits helped the Redskins extend their winning streak to four games and improve to 7-6. It was the second time this season that Cousins, a fourth-round draft choice out of Michigan State, filled in for an ailing Griffin. He had a touchdown pass but also threw two interceptions to seal the outcome in a 24-17 loss to the Atlanta Falcons on Oct. 7 after Griffin had exited the game with a concussion.

Things went much better for the Redskins this time after Griffin was injured on a hit by Ravens defensive lineman Haloti Ngata at the end of a scramble. Griffin left the game for one play, then returned for four plays, getting the Redskins within striking distance of a touchdown. But Griffin fell to his hands and knees after throwing the ball away and taking an intentional grounding penalty in the final minute, and Cousins took over for good.

“I could see he was limping after the second big completion,” Cousins said. “I then didn’t know what to do, didn’t know what the plan was. I just tried to find Coach [Mike] Shanahan just to be able to let him make the call and he said, ‘Where’s Kirk?’ And I said, ‘Here I am.’ He said: ‘Go out there. Take his spot.’ Coming out there, we wanted to make sure he actually was hurt and he said, ‘Yeah, I can’t do it.’ ”

After Griffin left the game for good, Cousins zipped a pass to wide receiver Leonard Hankerson for a 15-yard gain to the Baltimore 11-yard line. He found Garcon open on the right side of the end zone for the touchdown, then tied the score on the two-point conversion by weaving his way through Ravens defenders on a quarterback run more suited to Griffin’s skills than Cousins’s.

“I’m not as fast as Robert so those blocks are going to have to be made for me to score,” Cousins said. “And they were. I just had to dive across the goal line to do that last part of it.”

Said Redskins linebacker Lorenzo Alexander: “Everybody has to step up their game when he [Griffin] is not there. I think they did that. Kirk came in and did a great job moving the ball, throwing that touchdown to Pierre and also getting that two-point conversion. It was a team effort, and people had to rise their game up once he left the game.”

Shanahan and the Redskins received criticism for drafting Cousins in April after using the second overall selection on Griffin. But Shanahan made Cousins Griffin’s primary backup, ahead of veteran Rex Grossman. Cousins had impressive moments during the preseason, and he delivered Sunday.

“For me to put Kirk in that situation as the second-team quarterback so early in his career kind of gives you an idea what I think of Kirk,” Shanahan said.

Cousins said he will prepare for next Sunday’s game at Cleveland as if he will be the Redskins’ starter, but will step aside willingly if Griffin’s knee is sound.

“There’s no doubt that it’s been communicated to me by some veterans that they believe in me and if my name has to be called upon that they believe I can get it done,” Cousins said. “And that means the world. But first and foremost, Robert is doing an awesome job.”