Stoke striker Dave Kitson and defender Ryan Shawcross are to see specialists on Tuesday in order to diagnose the extent of respective knee and back injuries.
Both were substituted in Saturday's 1-0 victory over West Brom and scans on Monday highlighted potential problems.
"The injuries are all a bit of a mystery in both cases but hopefully the specialist can shed some light on just what is going on," said Stoke manager Tony Pulis.
"It's obviously a concern for us and for the players when you are in the dark, but we'll see what the scans bring before deciding our next step," he added.
"Either way, both Dave and Ryan could be struggling for Saturday."
Captain Andy Griffin will play against fellow Barclays Premier League newcomers Hull at the weekend despite breaking his hand against the Baggies.
"We'll get a plaster-cast sorted for his hand and that should mean he is all right to carry on playing," Pulis told the Stoke Sentinel.
"You know he's the kind who wants to be out there at all times."
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