Barca takes on Athletic Bilbao to open the 2019-2020 season but it will be without its inspirational captain.
Messi has not featured during pre-season due to a calf injury and he was not present in the open section of Barca's training session.
Ahead of the workout, former Athletic manager Valverde had suggested Messi would not be able to take his place in the squad.
"We're not going to take risks with players and certainly not with him," Valverde said. "He's not trained with the team since they came back and it's different to train in isolation.
"We'll wait a little to see how his recovery goes, it's going well I understand, but we have to wait and see."
Philippe Coutinho and Ivan Rakitic are included in the travelling squad despite reports they could leave Barca as part of a deal with Paris Saint-Germain for the potential return of Neymar.
Antoine Griezmann is in line to make his league debut for Barcelona after joining from Atletico Madrid, with fellow new arrivals Frenkie de Jong and Junior Firpo also included, but midfielder Arthur misses out.