ASHBURN, Va. -- All the medical terms associated with Robert Griffin III's knee injury can be boiled down to one simple message: It's not too bad.
Beyond that, there are still some very important unknowns.
The NFL's top-rated quarterback might or might not play Sunday when the Washington Redskins visit the Cleveland Browns. Coach Mike Shanahan, knowing full well that it makes the other team work extra to prepare for two quarterbacks, will no doubt wait as long as possible to publicly commit one way or the other to Griffin or fellow rookie Kirk Cousins.
"Both of them will have a game plan," Shanahan said Monday.
The interior of Griffin's right knee was the subject of intense scrutiny during Shanahan's weekly news conference, when it was shown that an injury to a franchise player like RG3 can flummox even a seasoned coach. Shanahan initially said Griffin had a "strain of the ACL" before later correcting the diagnosis to a sprained LCL, with the coach stepping away from the podium to demonstrate the location of the ligament involved.
The upshot: Griffin has a mild, or Grade 1, sprain of the lateral collateral ligament located on the outside of the knee, caused when he was hit by defensive tackle Haloti Ngata at the end of a 13-yard scramble late in regulation of the 31-28 overtime win over the Baltimore Ravens.
"When I looked at it on film," Shanahan said, "I thought it would be worse than it was."
The LCL is one of four ligaments in the knee. A Grade 1 sprain typically means the ligament is stretched or has some minor tears and usually doesn't require surgery. Griffin will get multiple treatments daily and will probably have to wear a brace for several weeks.
The next major benchmark is whether Griffin will able to take part when practice resumes on Wednesday.
"You're hoping with rehab it gets better very quickly," Shanahan said. "But we don't know for sure. ... He's definitely not ruled out for the Cleveland game."
Griffin's father, Robert Griffin Jr., said in a text message that his son was "feeling good" and that "we will know by Thursday" whether Griffin III will be able to suit up against the Browns.
The most severe knee injury usually associated with sports is a season-ending torn ACL, the anterior cruciate ligament. Griffin tore the ACL in his right knee while playing for Baylor in 2009, but Shanahan said Griffin's reconstructed ACL "looks great" and that there's "no problem there."
"He's doing good. He's in high spirits," left tackle Trent Williams said after speaking with Griffin on Monday. "It was a pretty nasty, awkward hit, and for him not to be seriously injured is a blessing."
No. 2 overall pick Griffin has become a phenomenon in his debut NFL season, leading the Redskins -- a team that went 5-11 last year -- to four straight victories to put the record at 7-6, one game behind the first-place New York Giants in the NFC East. His performance Sunday put him atop the league with a 104.2 passer rating, better than Peyton Manning, Aaron Rodgers, Tom Brady and everyone else.
Fourth-rounder Cousins might not be much of a drop-off, especially after his super-sub performance against the Ravens. When Griffin left for one play, Cousins converted a third-and-6 with a pass to Pierre Garcon that drew a pass interference penalty on Chris Johnson.
When Griffin left for good later in the drive, Cousins completed two passes in two plays, and his nice pump fake allowed Garcon to get open for an 11-yard touchdown with 29 seconds left in regulation.
Cousins then did his best RG3 impersonation, running the quarterback draw on the 2-point conversion to tie the game.
"You're running the scout team the majority of the time, and you're expected to go in there and perform," Shanahan said. "So there's a lot of pressure on people. Some people can handle it; other people can't. But when you prepare yourself like he has, it didn't surprise me that he was flawless in what he did."
Shanahan defended the decision to have Griffin return to the game for four plays after the injury, saying he left the decision in the hands of Dr. James Andrews, the renowned sports physician who is on the sidelines for most Redskins games.
"He's the one that gives me that information," Shanahan said. "It's way over my head."