The Raiders owned the No. 3 overall defense last year and provided the team its lone bright spot during a 2-14 season that was the franchise's worst since 1963. The defense was so much of a salvation for Oakland that when team owner Al Davis made sweeping coaching changes this offseason, coordinator Rob Ryan and most of his assistants were spared.

Kiffin isn't letting the defense rest, however. While most of his time is spent figuring out how to get more out of an offense that produced just 12 touchdowns in 2006, the NFL's youngest head coach is also taking a crash course in the Raiders' defense.

"I spend a lot of time with them," Kiffin said today. "That's so that I totally understand what we're doing and our philosophy there and our schemes.

"We go in every day after (practice) and we watch the film together as a whole staff so our whole staff understands it," he said. "The more offensive guys can hear them and vice versa, it just helps you as a staff."

Oakland's defense has improved each year under Ryan, son of former defensive guru Buddy Ryan. Two years ago, defensive end Derrick Burgess set a franchise record with 16 sacks and went to the Pro Bowl. Last season, cornerback Nnamdi Asomugha was third in the NFL with eight interceptions and was the cornerstone for the league's top-ranked secondary.

Things continue to be promising this year.

Warren Sapp reported to the team's mandatory mini-camp in April having shed nearly 50 pounds. Burgess, who is reportedly seeking a new deal with the Raiders, hasn't made the issue a problem though he has been noticeably absent from team's voluntary workouts.

Neither Sapp nor Burgess attended today's practice, and both also are expected to skip next week's three-day mini-camp.

One change the defense is undertaking is in the secondary, where safeties Stuart Schweigert and Michael Huff are breaking out of the traditional mode. Rather than having one play free and the other at strong, the Raiders are using Huff almost exclusively on the left side of the field while Schweigert is on the right.

"When we play the Chiefs or Chargers or something like that, I'll be down covering (Antonio) Gates and (Tony) Gonzalez, so it kind of just depends," said Huff, Oakland's first-round pick in 2006. "We can disguise a lot more. Before, we were in man on a lot of downs so any motion (and opponents) knew we were in man or zone because I'd be running across. Now if they motion, me and Stu stay right and left."

Kiffin feels the change in the secondary, along with a year of NFL experience, should benefit Huff, who started all 16 games as a rookie but had no interceptions.

"I think it really allows him to play faster because he's not so nervous about bad things happening," Kiffin said. "Sometimes so much pressure's on those guys that they don't play the way they played their whole life, so hopefully we'll get him back to that."

Russell and veteran quarterback Josh McCown split time running Oakland's first-team offense on Wednesday.

Missing was Andrew Walter, the third-year player who quarterbacked the Raiders to their only two wins last year. Kiffin said Walter underwent arthroscopic knee surgery on Monday and is expected to be out 4-6 weeks.