GREEN BAY, Wis. -- Javon Walker, the Green Bay Packers' best receiver, will miss the rest of the season after tearing up his right knee in the opener. Walker will need an operation once the swelling subsides to repair the torn anterior cruciate ligament and will require between eight and 12 months of rehabilitation. "Talking to him last night, he's very positive and upbeat about it, understands what's ahead of him and is planning on breaking all kinds of records on getting back sooner," coach Mike Sherman said Monday. Walker was hurt in the third quarter of the Packers' 17-3 loss at Detroit on Sunday when he pushed off safety Terrence Holt on a 55-yard catch that was negated by his offensive interference. Walker, who made the Pro Bowl last season after catching 89 passes for 1,382 yards and 12 touchdowns, threatened to hold out this year if the final two years of his contract weren't renegotiated. But he showed up in training camp on time, saying he wanted to prove he was worthy of a blockbuster contract through his play. The risk, of course, was suffering a serious injury that would limit his earning power -- just like the one he suffered Sunday, when he caught four passes for 27 yards. He's due $515,000 this season, the fourth of a five-year deal he signed in 2002 for $7.485 million. When he was threatening to hold out, agent Drew Rosenhaus said he couldn't let Walker risk his health for that kind of money, but Walker said he couldn't fathom missing any games in a contract dispute. With Walker down, Robert Ferguson will start alongside Donald Driver, who will move from split end to flanker. Ferguson is the Packers' best special teams player, but might be taken off those units now, Sherman said. Also, second-round draft pick Terrence Murphy, who missed much of training camp with a knee injury, will be force-fed the offense so he can serve as the No. 4 receiver behind kick returner Antonio Chatman. Walker's injury is a serious blow to the Packers and quarterback Brett Favre, whose team had never been held to as few as three points in any of his 226 consecutive starts, counting playoffs. "I don't think there's going to be desperation in the locker room. There's disappointment for him personally and for our team," Sherman said. "But you have to be able to move on."