Wales flanker Justin Tipuric could sit out the rest of the PRO12 season with the Ospreys as he comes back from a concussion.
Tipuric suffered a blow to the head playing for Wales in their final Six Nations match against Italy.
With Tipuric’s long-term health in mind the Ospreys are making no effort to rush him back and are allowing the British and Irish Lions back-row to take as much time as he needs to recover.
That could mean that Tipuric, 26, misses the rest of the domestic campaign in order to get healthy for Wales three-Test tour to New Zealand later this year.
“We’re not even putting any thought process around when the next game for Justin can be,” Rees told the BBC.
“It may be we just sit tight and see the season out and get to the June.
“He was in the office last Friday and he had a tough old week of it in terms of just being inactive at home and really not being comfortable getting out and about.
“And we’re not putting any pressure on him having to do anything but sitting on the sofa.
“You’ve got to be really wary and sit back and look at the long-term betterment of these players.”