CHARLOTTE, N.C. -- Left tackle Matt Kalil had arthroscopic surgery on his right knee Monday, meaning the Carolina Panthers could be without three linemen who began training camp as starters when they open against the Dallas Cowboys on Sept. 9.
Dr. James Andrews performed the surgery in Florida after Kalil missed consecutive days of practice complaining of soreness. Team trainer Ryan Vermillion said Kalil will be evaluated on a week-to-week basis, which doesn't entirely rule him out for the opener.
The Panthers lost starting right tackle Daryl Williams to a torn MCL and a dislocated patella early in camp. He could begin the season on injured reserve with the possibility of returning for the second half of the season, although he was on the field working on the side on Tuesday for the first time.
Left guard Amini Silatolu suffered a torn meniscus; there is no timetable for his return.
Taylor Moton, who began training camp battling Silatolu for the guard spot, had been playing right tackle. He was moved to left tackle when Kalil missed Sunday's practice and has been there ever since.
Jeremiah Sirles has replaced Moton, a second-round pick last year, at right tackle.
Kalil had been dealing with soreness in his knee since camp began, and according to coach Ron Rivera, it all "came to a head.''
"Absolutely concerned," Rivera said on Monday before Kalil's diagnosis was confirmed. "You've got three potential starters right now that are missing time. It's going to be tough. But as coaches, we have to continue to do the best job to make sure everybody gets prepared."
The rash of injuries on the line is similar to what Carolina experienced in 2016 when left tackle Michael Oher was placed on injured reserve with a concussion and Pro Bowl center Ryan Kalil was dealing with a shoulder injury.
Rivera said it was too early to call this situation catastrophic because the team still has three weeks before the season, and there is time to prepare other players for a starting role.
"We have time,'' Rivera said after Tuesday's practice. "We have time to evaluate and look at guys. The guy that has been stellar has been Taylor. We've been able to move him around. He seems to adapt very nicely.
"And we have a group of young guys that have stepped up. They're competing. This is going to be a real tough decision with all these young guys.''
Pro Bowl center Ryan Kalil was with his brother for the procedure.
"I talked to him before he went in,'' Ryan said. "Obviously, he was bummed, but he made it sound pretty optimistic we'll get him sooner rather than later.
"The next guy in is going to be Taylor, and he's doing a great job for us right now.''
While Rivera liked the depth Carolina had on the line entering camp, he admits the injuries have taken their toll. General manager Marty Hurney likely will have to sign another lineman or possibly trade for one.
Former general manager Dave Gettleman strapped Hurney as far as looking for another tackle during the offseason when he signed Kalil to a five-year, $55.5 million deal before last season.