A day after appearing to injure his left leg during a passing drill, Randy Moss missed two practices with the New England Patriots on Thursday.
Moss, acquired from Oakland in a trade during the draft, pulled up midway through Wednesday's practice. Trainers applied ice to his upper left leg, and he later left the field under his own power.
Asked about a timetable for Moss' return, Belichick said, "My crystal ball's no clearer than yours."
Moss was injured while running under a deep ball thrown by Tom Brady. The two had connected on similar plays throughout camp.
"I think they understand that he's here because he wants to win," Patriots owner Robert Kraft said of Moss, who accepted a one-year contract at a reduced salary to play for New England.
Linebacker Warrick Holdman was hospitalized with a spinal cord concussion following a collision with a teammate during training camp.
Holdman was carted off the field strapped to a backboard and taken by ambulance to Sky Ridge Medical Center, where he was being kept overnight for observation, team spokesman Jim Saccomano said.
Holdman temporarily lost feeling in his extremities but had movement in his arms and legs by the time he was taken off the field. He appeared to hit the crown of his helmet on another player's helmet.
He is a ninth-year pro in his first season in Denver after spending the last two years in Washington.
Rookie running back Adrian Peterson left practice with an injury after taking an elbow to his hip while catching a pass in a drill. He said it wasn't serious, calling the injury a minor hip pointer.
Peterson missed the first five practices of training camp before signing a five-year, $40.5 million contract on Sunday. His status is day to day, but he's unlikely to participate in weekend scrimmages against Kansas City.
Terrell Owens returned to practice for the only workout of the day. He was back on the field in full uniform and taking part in drills.
Owens sat out both workouts Wednesday, a day after coach Wade Phillips had the receiver take it easy to rest a sore hamstring. Phillips said Wednesday that Owens wasn't injured.
Owens missed 14 straight workouts in training camp last year because of a hamstring problem, though an MRI showed no major problems.
Defensive end Mario Williams missed practice with a tight hamstring, but he and coach Gary Kubiak said it wasn't serious. Williams watched with a large bandage wrapped around the top of his right leg. The problem began Tuesday morning, and he was pulled from the field halfway through the workout. The No. 1 pick in last year's draft, Williams said it was mostly a precaution and he wasn't worried about the problem lingering.
Harris will likely step in right away as the starter at strong safety next to veteran Mike Minter. Nate Salley had been working with the first team until injuring his right knee in practice Wednesday. Salley sat out practice Thursday and is day to day.
Free agent safety Oliver Celestin signed a one-year contract. The 6-foot, 207-pound Celestin is a four-year NFL veteran who played in 13 games last season with Seattle and had nine tackles.
Tight end Nate Lawrie signed a one-year contract to bolster a position severely thinned by injuries in training camp. The Bengals waived undrafted rookie linebacker Cameron Siskowic.