NORMAN, Okla. -- Oklahoma defensive captain and leading tackler Travis Lewis will miss up to eight weeks with a broken bone in his left foot, leaving the Sooners without one of their best defensive players for a few crucial early season games.

Athletic trainer Scott Anderson said Tuesday that Lewis' injury will not require surgery, and will be treated with rest and immobilization. Lewis, chosen as the Big 12's preseason defensive player of the year by the media, was injured Monday during Oklahoma's first practice in pads of training camp.

"We're disappointed for Travis," coach Bob Stoops said in a statement. "He has worked very hard and I know he'll want to get back as quickly as possible.

"We'll adapt in the meantime. We've recruited very well and have some excellent athletes in those positions. I'm confident that those players will perform well."

If Lewis is out eight weeks, he would miss Oklahoma's first four games -- including a Sept. 17 trip to Florida State and a Sept. 24 rematch against Missouri, which beat the Sooners last season to knock them out of the top spot in the BCS standings.

The Red River Rivalry game against Texas on Oct. 8 is 8½ weeks away.

When Stoops spoke after practice Monday, he knocked on a wooden podium after saying that the Sooners have "had five days now, we don't have anybody that's not practicing." Now, he's shuffling his defense to make up for the absence of one of the team's leaders.

Stoops said sophomore Corey Nelson will take over Lewis' outside linebacker spot on the weak side. An experiment to move Tony Jefferson from the Sooners' hybrid nickelback/outside linebacker to free safety will end, and Javon Harris will move to the top of the depth chart at safety.

The injury will diminish Lewis' chances at becoming the first player ever to lead the Sooners in tackles in four straight seasons. Lewis made 109 tackles last season, giving him 362 for his career -- the ninth-best total in Oklahoma history.

His eight career interceptions are tied for the most by a Sooners linebacker.

Lewis announced in January that he wouldn't enter the NFL draft and instead was "coming back to win a national championship, point blank." He said that "anything else would be a disappointment."

The Sooners are ranked No. 1 in the USA Today preseason coaches' poll. The Associated Press' rankings will be released Aug. 20.