ALAMEDA — Raiders right defensive end Tommy Kelly stayed down after he injured his right knee early in the third quarter of Sunday's game against the Tennessee Titans. He needed crutches to get around the locker room after the game.

Now comes word that Kelly's injury is every bit as bad as it looked at the time, according to Raiders coach Lane Kiffin on Monday.

"It doesn't sound good," Kiffin said. "We'll know more Wednesday, but it doesn't sound good at this point."

Losing Kelly would be a significant blow to a Raiders defense that has played well the past two games after struggling the first five games. Several players cited Kelly's play as a primary reason for the defense's resurgence.

Kelly does not grant interviews, so he was unavailable for comment. His status will be evaluated today and an update provided Wednesday.

Rookie Jay Richardson replaced Kelly on Sunday and likely would start if Kelly is unable to play Sunday against the Houston Texans.

QB FOLLIES: Another week, another go-round of guess who the quarterback is this week?

Opening-game starter Josh McCown missed his fourth straight game Sunday because of a broken left big toe he sustained against the Cleveland Browns on Sept.23. He said he is about 85-90 percent healed and hopes to be 100 percent by Friday.

"It's getting there but it's not full go yet," McCown said Monday. "We're pushing it as hard as we can, as fast as we can."

Kiffin said once again that he won't make a determination on whether McCown or Daunte Culpepper will start against the Texans until he sees how McCown fares in practice.

"We'll see Wednesday what Josh looks like and what he can do out there and then start figuring that out," Kiffin said.

McCown has worked out each of the past three Mondays as a means of gauging his mobility. He said Monday that he encounters difficulty only when he moves laterally.

On Sunday, former Raiders quarterback Rich Gannon, now an analyst for CBS, said during the broadcast of the Titans game that Culpepper isn't as mobile as he once was and takes too long dropping back after taking a snap.

"I don't feel that way," Culpepper said. "I've been working very had to get back from under the center. My coaches have let me know that I'm getting back to perfect timing."

Kiffin conceded that Culpepper isn't as quick dropping back as McCown and that the Raiders compensate by using the shotgun formation more than usual. Culpepper was sacked five times and fumbled four times against the Titans.

Culpepper took umbrage with Gannon's assessment.

"For him to say I'm not the same player, that's false," Culpepper said. "I'm a lot better now. I've had time to mature and see the game from a different aspect. I feel like I'm getting better every day. At the end of the day, I'm going to show them that they're wrong if they feel that way."

RAIDERS TARGET DWIGHT: The Raiders have offered wide receiver and kick returner Tim Dwight a one-year contract, a person in the front office said. Dwight is expected to sign the offer, perhaps as soon as today. If he does, veteran receiver Mike Williams is the logical candidate to be released.

Williams has struggled carving out a niche in Oakland's offense and has committed more than his share of mistakes.

Dwight, 32,worked out for the Raiders two weeks ago but was not offered a contract. He has played for the Atlanta Falcons, San Diego Chargers, New England Patriots and New York Jets during his nine-year NFL career. He has averaged 23.4 yards on kick returns and 9.8 on punt returns in his career. He also has 188 receptions for 2,866 yards and 17 touchdowns.

EXTRA POINTS: Kiffin said he doesn't intend to carry four quarterbacks for the rest of the season. Third-year player Andrew Walter is the odds-on candidate to go. ... Kiffin dismissed recent reports that running back Dominic Rhodes is on the verge of being released. "The first thing I did was, I went to Dominic and said I have not had any conversations with anybody about that," Kiffin said. ... Kiffin said he anticipates rookie running back Michael Bush being removed from the physically-unable-to-perform list and added to the 53-man roster. Bush has been on the PUP list since the start of training camp while recovering from a broken right leg he sustained in his first game at the University of Louisville last year.