The Washington Redskins quarterback is recovering from a double knee ligament tear and is a doubt for the start of the 2013 NFL season.
The team's backup QB told NFL AM: "Robert looked awesome. I'm not just saying that. Obviously, he is a bit of a freak in terms of his athleticism, but he's healed very quickly.
"He couldn't practice with us, he was on a spate field doing drills all spring ... he looked really good, and I think he'll be ready to go in week one. But obviously my mindset is to be ready no matter what. And I'm getting ready all summer, so I can be ready if called upon.
"I think I have to be prepared to be a starter in this league, if I get called upon. I'm still expected to go in there, to play well and lead the Redskins to victory. So I have to be able to play like I am a starter in this league. Otherwise, I won't be in this league much longer."
Griffin was named the league's offensive rookie of the year in 2012.