Jordan Stewart and Trevor Benjamin are both absent through injury, whilst Callum Davidson is out with a ban following his dismissal against Sheffield United.
Adams is happy with how the duo are progressing on their road to recovery but they are still expected to miss the matches against Southampton and Chelsea.
"They are both progressing nicely, but neither will be ready for the start of the season," said Adams to the club's official website.
"Jordan is doing plenty of physical work and running but cannot do anything at the moment that would involve contact with the shoulder.
"Hopefully we might have him available around September. Benjamin is also recovering, but he certainly won't be fit to start the season."
