The National Football League is still aiming to start its 2020 season on time on September 10, but chief medical officer Allen Sills said Tuesday it remains unclear when players will be welcome to train at club facilities.
"We are not putting dates on the calendar at this point," Sills said after NFL owners held a virtual meeting on Tuesday.
Traditionally clubs bring players in for mini training camps in June.
But club facilities have been closed amid the coronavirus pandemic, with only a limited number of non-player and non-coaching staff allowed to return, starting on Tuesday.
Which teams could welcome staff back to their offices was dependent on local government lockdown rules and only a handful of clubs made the move on Tuesday.
Dallas Cowboys owner Jerry Jones called it a "big day" for clubs all over the league as he attended the virtual meeting from his office at the team's practice facility.
"It's great to be back in the office this morning," he told the Cowboys website. "I thought there was no better place for me to participate in our virtual league meeting today than right here at my desk at The Star."
While players needing medical attention can be treated by team staff at team facilities, healthy players and coaches will not be able to work there until local regulations allow all 32 teams to do so.
Jeff Pash, the league's general counsel, said the goal would be to maintain a level playing field.
"Certainly our goal will be to have all 32 clubs operating on a consistent basis."
For now, the league and players union are discussing what health and safety protocols must be in place when training camps open.
"We fully expect we will have positive (Covid-19) cases that will arise," Sills said, adding that the league was formulating plans to deal with cases efficiently so as to prevent the spread of the virus.