Manager Steve Coppell said the duo were not likely to feature "as a precaution", while defender Louis Carey will also miss out with a cut heel.
"We've had a few little mishaps which is something I'm not best pleased with, but it happens," Coppell said.
Carey, who cut his heel in a domestic accident, is yet to train with the club since they returned for pre-season.
The Robins will play Swedish top-flight sides Gothenburg and Helsingborgs, as well as tackling lower league Vallens IF.
Once we start playing games, you find out where the holes are and try to fill them
Bristol City manager Steve Coppell
"I like to go away to get the team to express themselves without the result being all important," Coppell added.
The tour was arranged at short notice after Coppell took the helm at the club at the close of last season and as a result the club are playing tougher opponents than the manager anticipated.
"We face two tough opponents," he said. We'll have to get up to speed quicker than anticipated."
Coppell added that he expected transfer activity at the club to speed up in the run-in to the season's start.
"Once we start playing games, you find out where the holes are and try to fill them," he said.
City have so far made two summer signings, Barnet winger Albert Adomah and Reading utility player Kalifa Cisse.
Source: BBC Sport
Source: BBC Sport