NASHVILLE, Tenn. — All the critics who bashed Tennessee's decision to draft running back Chris Johnson with their first-round pick in April sure look foolish now.

The rookie leads the AFC with 715 yards rushing and 819 yards from scrimmage, and he trails only Washington's Clinton Portis (944), Adrian Peterson of Minnesota (823) and Michael Turner of Atlanta (794) for the NFL rushing lead. Each of the backs ahead of him have at least 30 carries more than Johnson.

Yes, Johnson is enjoying his success.

"I know I have quieted the critics," Johnson said Wednesday. "They really have nothing to say now but give coach (Jeff) Fisher and the rest of the staff kudos on the pick that they made."

Johnson was the 24th pick out of East Carolina, and an easy one for the Titans, who loved his speed. Halfway through the season, Johnson already ranks fifth in franchise history for yards rushing by a rookie — chasing the standard set by Earl Campbell (1,450) in 1978 and nearly matched by Eddie George (1,368) in 1996.

Fullback Ahmard Hall, who helps clear holes for Johnson, said stopping the rookie remains a challenge for opponents.

"You still have to stop him. We've got a great offensive line, and CJ is getting better and better each week. That's bad for other teams because he's maturing and getting better each week. You're not going to be able to contain him too much longer," Hall said.

The Titans (8-0) also have LenDale White, who has bolstered the NFL's fourth-best rushing offense this season. White leads the NFL with 10 touchdowns rushing and ripped off a 54-yard run in last week's 19-16 overtime win against Green Bay.

But it's Johnson's speed the Bears (5-3) will pay attention to when the Titans visit Chicago on Sunday.

"We play some pretty good running backs in our division here, but he's probably the fastest guy we'll play all season long," Bears linebacker Brian Urlacher said in a conference call Wednesday. "I've watched him on film in some of their games this year, and he's a good back."

Chicago coach Lovie Smith said the Bears took a good look at Johnson heading into the draft before taking Matt Forte out of Tulane with the 44th pick in the second round. Forte ranks second among rookies with 641 yards rushing.

"Whenever you see a guy that can accelerate as fast as he can and you know what type of speed he has and then you look at his production too, of course it will get your attention. I can't say I'm completely surprised at how he's played. I thought he'd be a very good football player in the league," Smith said of Johnson.

The Titans gave Johnson the ball a season-high 30 times against Green Bay. He ran 24 times for 89 yards and a TD and had six catches for 72 yards.

Johnson said he feels he's handling the demands of splitting work with White, and Fisher said the Titans are trying to do more with the rookie each week.

"He's making different catches and different runs and different cuts," Fisher said. "He's a complete back. He can catch and accelerate and go and carry the football, and he's also doing a good job protecting for us."