SANTA CLARA, Calif. -- San Francisco 49ers linebacker Patrick Willis underwent an MRI exam Monday on his injured right hamstring, but his status for this weekend's game at Arizona is unclear.
Coach Jim Harbaugh said he didn't know the severity of the four-time Pro Bowl linebacker's injury or if it could sideline him for the NFC West champion 49ers (10-2), who clinched their first division title and playoff berth since 2002 with a 26-0 victory over the St. Louis Rams on Sunday.
"Nothing to share," Harbaugh said. "I'm not in Patrick's body. It's hard to say with any injury, including a hamstring. ... I guess I was more relieved that it wasn't a knee. That area that they were working on -- I was concerned about that, for Patrick and for our team."
Willis landed awkwardly after missing a tackle on Rams fullback Brit Miller during an 18-yard pass from A.J. Feeley in the first quarter. Willis was briefly down before being helped off the field by trainers, and he watched the rest of the game from the sideline.
Willis, the heart of the 49ers' top-ranked run defense, has 93 tackles, 2.0 sacks, a career-best four forced fumbles and an interception. In May 2010, he received a five-year, $50 million contract extension that takes him through the 2016 season and includes $29 million in guaranteed money. He earns $10 million per season.
"I know Pat is a hard player, and I was like, 'It has to be something serious for him not to just get back up and get back in the game,'Â " 49ers defensive lineman Ricky Jean Francois said.
The 49ers can afford to rest Willis to ensure he's at full strength for the playoffs next month. But Harbaugh insists the fact they already won the NFC West wouldn't have any bearing on playing time for guys like Willis or running back Frank Gore.
"The trainers and Patrick will give feedback there and make a decision," Harbaugh said.
Copyright 2011 by The Associated Press.
