The 25-year-old suffered a knee injury during the Villains' pre-season tour of the United States and is expected to miss the start of the new Premier League campaign.
"It is a blow because in pre-season Gabby has done really well and against Chicago, before his injury, he was unbelievable," the Birmingham Mail quotes Delph as saying.
"The boys are disappointed, but I'm sure in a few weeks he will be back with us and he seems pretty confident because he's naturally fit.
"I think a few of the lads feared the worst and I certainly did because he's a good friend of mine."
Villa kick off their campaign at home to West Ham United on August 18.