The knee injury suffered Sunday by rookie quarterback Robert Griffin III is mild enough that the Washington Redskins hope he will be ready to play in their game this weekend at the Cleveland Browns, Coach Mike Shanahan said Monday.

Shanahan said Griffin suffered a Grade 1 sprain of the lateral collateral ligament in his right knee when his leg was twisted awkwardly on a hit by Baltimore Ravens defensive lineman Haloti Ngata late in the fourth quarter of the Redskins’ overtime triumph Sunday at FedEx Field.

Griffin will have to demonstrate on the practice field this week that he is able to play Sunday against the Browns, Shanahan said. “He’s definitely not ruled out for the Cleveland game,” the coach said.

Griffin was not available to comment. His father, Robert Griffin Jr., wrote in a text message to a Washington Post reporter who asked about the quarterback’s chances of playing Sunday: “That is the plan.”

Redskins left tackle Trent Williams said he also spoke to Griffin on Monday.

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)

“He’s doing good,” Williams said. “He’s in high spirits. It was a pretty nasty, awkward hit, and for him not to be seriously injured is a blessing.”

A Grade 1 sprain is the least severe type of that injury. The ligament is merely stretched, not partially torn, as it is in a Grade 2 sprain, or completely torn, as in a Grade 3 sprain. According to literature from the National Athletic Trainers’ Association, an athlete with a first-degree sprain “may be able to continue to play or will usually return to play in a few days.”

Former NFL quarterback Brett Favre, then with the Green Bay Packers, played with a sprained LCL in his left knee during the 2002 season. Favre suffered the injury during a game against the Redskins but had a bye week to heal before he played again. But running is a bigger part of Griffin’s game than it was for Favre.

Shanahan said Monday that Griffin was experiencing mild swelling in his knee. No other ligaments were damaged, according to Shanahan, including the anterior cruciate ligament in the same knee that Griffin tore in 2009 at Baylor. Tests showed no problem with Griffin’s ACL this time, Shanahan said.

Griffin will receive treatment and will be evaluated daily, said Shanahan, who added that he didn’t know whether Griffin would be ready to practice Wednesday. Redskins players are off Tuesday. Shanahan said Griffin might wear a brace on the knee.

“We’re going to do what we think is in Robert’s best interests,” Shanahan said during a news conference at Redskins Park. “And usually when you do that, it’s the team’s best interests as well. We’re not going to put him out there if we think he’s not completely healthy and he can’t do the things that help us win.”

Griffin left the game for one play Sunday after he was injured, then returned for four plays before exiting for good. Shanahan said Monday he sent Griffin back into the game after orthopedist James Andrews, who was on the Redskins’ sideline, told him that Griffin could play.

Fellow rookie quarterback Kirk Cousins, who took over for Griffin against the Ravens , would make his first NFL start against the Browns if Griffin is unable to play. Cousins threw a touchdown pass and ran for a tying two-point conversion with 29 seconds to play to force Sunday’s game into overtime. The Redskins won, 31-28, to extend their winning streak to four games and improve their record to 7-6.

They’re one game behind the first-place New York Giants in the NFC East and one game in back of the Chicago Bears and Seattle Seahawks in the race for the NFC’s two wild-card playoff spots. So the stakes are high for the Redskins, but they are unlikely to take any risks with his long-term health.

“His health is far more important than any game we’ll play this season,” Williams said in a conference call with reporters. “His well-being is the only thing he should be worried about at this time because it’s really not worth injuring more, if he is at risk. So, I mean, it’s all up to him and what the situation is.”

Said Shanahan: “If a guy can’t play at full speed, if he’s playing on one leg or 70 percent, there’s a good chance he could further injure himself. We’re not going to put him in that situation.”

Cousins said late Sunday he would prepare to be the team’s starter this week but would step aside willingly if Griffin is able to play. Cousins prepared to start in October after Griffin suffered a concussion against the Atlanta Falcons. But Griffin was cleared to practice and play, and started the Redskins’ next game Oct. 14 against the Minnesota Vikings.

— Staff writer Dave Sheinin contributed to this report.