Linebacker Patrick Willis and offensive tackle Joe Staley each have started every game this season while not only establishing themselves as two of the league's top rookies, but also two of the top performers this year for an underachieving 5-10 team.

"It's hard to say where you put the expectations for rookies at, but I would say both guys have exceeded that and played very well," 49ers coach Mike Nolan said yesterday.

Willis, the No. 11 overall selection in April, leads the NFL with 162 tackles and is virtually assured of finishing as the league champion in that category. Entering Sunday's season finale against the Cleveland Browns, Willis has a wide lead over Denver's D.J. Williams, who is second in the NFL with 133 tackles.

Willis was named the league's Defensive Player of the Week for the second time this season after his standout performance in last week's 21-19 upset over NFC South champion Tampa Bay.

Willis had 20 tackles — the most ever by a San Francisco player in a game since the NFL began recording tackles as a statistic in 1994 — to go along with two sacks, one forced fumble, one pass defensed and one quarterback hit. According to 49ers' coaches' review of game films, Willis has a team-record 210 tackles this year.

Willis is a strong favorite to be named NFL Defensive Rookie of the Year at the end of the season and is gaining support as a candidate for NFL Defensive Player of the Year honors.

"I just wanted to come in and try to be the best that I can possibly be as a rookie," Willis said. "My goal was just to come in and show the 49ers that they made the right choice taking me with their first selection."

The same is true for Staley, the No. 28 overall pick in April. To obtain the Central Michigan product, the 49ers traded their 2008 first-round selection to New England during draft weekend. That pick now will be a top-10 selection for the Patriots in next year's draft.

But Staley has been worth the high price. He beat out incumbent Kwame Harris for the starting position at right tackle during training camp and has been one of the steadiest performers on an offensive line that has struggled to approach its quality play of last season.

"Any time you get drafted that high in the first round, the team has expectations for you and you have expectations for yourself," Staley said. "To fulfill that, that's just something what you need to be. The franchise is putting a lot of money and a lot of stock into you playing well and playing at a high level.

"I know coming in as a first-round pick, I wanted to make an impact on this team and show them that they made the right decision. So you put that pressure on yourself to perform every week."

When Staley starts at right tackle against the Browns, he'll become the first rookie offensive lineman in San Francisco's 62-year history to start all 16 games in his rookie season. The only other rookie offensive lineman to do that for the 49ers was Cas Banaszek in 1968, when the season lasted 14 games.