The Argentine has yet to feature this season due to a calf problem and Barca were forced to deny rumors this week that he has suffered a setback to his recovery.
The suggestion is that Barcelona are simply being careful with Messi which means the team are expected to be without him again at the weekend.
Frenkie de Jong was back training with the group on Thursday, while Ansu Fati and Carles Perez were once again in attendance.
Saturday’s fixture is the last before La Liga pauses for the first international break of the new season. The break will give Messi more time to recover before the champions return to action against Valencia on September 14.
Meanwhile, Osasuna opened up with a 1-0 win over Leganes and followed that with a 0-0 draw against Eibar.