Dons supporters were alarmed when the official Aberdeen FC Twitter account posted this message on Thursday:
Derek - Jonny will miss at least the next two games. It's unfortunate but gives someone else an opportunity.
— Aberdeen FC (@AberdeenFC) February 19, 2015
Hayes had limped off with a hamstring injury on Hamilton's plastic pitch during last week's farcical 3-0 win.
The winger has been outstanding in several positions for Aberdeen this season, and Dons boss Derek McInnes says it will be a blow to lose him.
"We'll just have to get on with it," he said, "but I don't think there's been many, if any, who have been better than Jonny this season.
"He's been excellent whether its been wide right, wide left, in the middle of the park or at left-back.
"He is a really good competitor and has been a key player and his flexibility and pace has been really important for us.
"He also missed the last Celtic game as well as his wife went into labour on the morning of the match so it's disappointing that he won't be available for the game at Parkhead.
"But we are concentrating on St Mirren first this weekend and the good thing is we have a really strong squad. So someone else will get their chance now."
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