The 22-year-old Welshman damaged his ankle during the Blues' shock 18-16 loss to Connacht and is now awaiting further news on the extent of the injury.
The setback comes 12 weeks after Roberts was forced to leave the Loftus Versfeld pitch early in the second-half of the Lions' heart-breaking second-Test defeat to the Springboks on June 27.
The wrist injury the medical student sustained that day had seen him sidelined until the weekend and, although he was delighted to be back involved in Galway, Roberts could now face a further spell out of the game.
"I hurt the ankle after about half an hour and was only running at about 70% so I came off at half-time," said Roberts.
"It was great to be back playing. But we were absolutely gutted with the result; the changing room told the story."
And while Roberts and Blues coach Dai Young were hoping that tests show the injury is only a minor one, former Lions centre Mark Taylor told BBC Radio that Roberts' potential absence would be a huge blow for Wales' hopes of a successful autumn series against New Zealand, Samoa, Argentina and Australia.
"They will want him back and firing on all cylinders for the November Tests," said Taylor, who was a Lions tourist in Australia eight years ago.
"Jamie was superb during the summer. He's such a big-game player and such a threat in every aspect.
"He's obviously strong and a big runner with the ball, but he's also very quick and has good hands.
"He would be a big miss and obviously a concern for Wales. I just hope that the news on Jamie is not too bad."