Sam Allardyce was left counting the cost of the 2-0 pre-season defeat at Dundee United.
The trio all limped out through injury early on in the match with next Saturday's clash with Manchester City just a week away.
"Unfortunately I think from our point of view that the game was over when Gally, Ryan and Chris got injuries, and they are looking pretty serious as well for next week," Allardyce told the club's wesbite.
"We will just hope and keep our fingers crossed through the week that we can get some of them fit.
"Given that we have international week we can ill afford anybody else getting injured away there.
"So we'll have to tread carefully next week unfortunately but the situation is something we'll have to cope with and get the best side out we can against Manchester City and hope they are fit enough and ready enough to go and do battle with them.
"With Ryan it looks like a medial ligament, and Gally and Chris are hamstrings. We'll know better as to how seriously they are injured on Sunday and Monday when we get scans on them obviously.
"But all three are pretty doubtful for next week."