Johnson, who has missed Detroit's last two games with a sprained ankle, said his ankle is feeling significantly better than it was in recent weeks, according to Dave Birkett of the Detroit Free Press.
While Johnson's ankle is making progress, a decision on whether he will play in London might not come until Sunday.
"You can go out there and tweak it again and then you're almost back where you were. Or you could try to rest it and let that thing get all the way right," Johnson said. "That's exactly where we're at right now, trying to figure out."
"Things are going good," he said. "We're moving in a positive direction."
The Lions have won their last two game despite the absence of Johnson, who is currently second on the team in receiving yards (348) and tied for the team lead in receiving touchdowns (two).
Detroit's top two tight ends, Eric Ebron and Brandon Pettigrew, and starting running back Reggie Bush missed practice on Wednesday and Thursday, leaving their status uncertain for the Week 8 contest against Atlanta.
- Brad Rowland