INDIANAPOLIS -- You can take Aug. 2 out of the equation when it comes to Indianapolis Colts linebacker Robert Mathis returning to the practice field.

That's according to Colts owner Jim Irsay.

Robert Mathis led the NFL in sacks with 19.5 in 2013. John Rieger/USA TODAY Sports

At this point, it's anybody's guess when Mathis will make his return from his torn Achilles, which occurred while he was working out during his four-game suspension for using performance-enhancing drugs at the start of the 2014 season.

"I don't think at this point anyone knows for sure," Irsay said. "Obviously Robert is optimistic and he's a fast healer. You just don't know. I would say I don't see him being football-ready for the start of training camp, where he would be a full-go guy and that sort of thing."

Mathis was asked on May 31 on WTHR, Indianapolis' NBC affiliate, whether he planned to be on the field at the start of training camp.

"I said I meant it, I'll be ready [in] September," Mathis told the station during the interview.

While the Colts obviously would like Mathis back in the lineup, Irsay doesn't sound as hopeful. The Colts report to training camp at Anderson (Ind.) University on Aug. 1 and will have their first practice the following day. Mathis led the NFL in sacks with 19.5 in 2013.

"Time will tell," Irsay said. "Obviously Robert wants to be back as soon as he can be. We want him back as soon as he can be. But we also want to make sure when he comes back that he's 100 percent healthy and ready to go. Again, I talked about early November [at NFL owners meetings in March]. It could be sooner than that certainly. But as far as the start of training camp, I don't see him being a full-go guy as we're starting up in Anderson."