Midway through Saturday afternoon's practice, Williams was backpedaling during a passing drill, then stopped to change directions. His left knee buckled, and he dropped to the ground, pounding his fist on the turf. Childress said Sunday that Williams suffered an injury to his kneecap, which will probably end his season before it began. Childress said there wasn't any ligament damage to the knee, which required ACL surgery after an injury in 2004.
"I feel terrible for Tank," Childress said. "Injuries are one of the toughest things (about this job), and season-ending injuries are even tougher."
With Williams gone, Dwight Smith, who signed a few days before training camp began, will be in the starting group opposite Darren Sharper. Injuries are starting to pile up for the Vikings, who have also lost running back Chester Taylor, linebacker Chad Greenway and defensive tackle Kevin Williams for portions of practice over the last two days.
Childress said that Taylor has a sore left groin, an injury suffered Friday against Kansas City. The running back, one of the team's marquee free-agent signings, attended practice Sunday in full pads but did not participate in any of the team drills.
Greenway, the Vikings' first-round draft choice, suffered a concussion during a goal-line drill Saturday and left the field. He attended Sunday's practice in a jersey and shorts, and he's expect to be back Sunday afternoon for a short special-teams workout.
Williams had some swelling on his right knee, which Childress described as a chronic condition. Childress said that Williams will be monitored and should return to practice soon.
The injuries occurred during the most physical practice of training camp. Childress said that contact is inevitable at training camp, but he's searching for the right balance to avoid injuries.
WILLIAMSON CONTINUES STRONG CAMP
With Marcus Robinson attending a family funeral, second-year receiver Troy Williamson is taking advantage of time with the starting unit, making several nice catches, some deep and some diving, over the last two days.
"I feel like everything is coming together," he said. I'm just doing what I need to do."
Childress said that when he was hired, his opinion was that Williamson was strictly a speed receiver, only capable of making plays down the field. But as he's watched Williamson, Childress said that opinion has changed.
"He's niftier, more nimble, he has more wiggle than I thought," Childress said.
Childress said that Williamson has shown good hands and the ability to go over the middle and catch balls in traffic.
Robinson is expected back in Mankato Sunday night and should practice Monday.