Fabricio Coloccini has suffered a setback on his return from injury.
Newcastle United's captain, sidelined since February, returned to training at the relegation-threatened club this month.
But Rafa Benitez today revealed that the defender had suffered a "reaction" on the practice field.
And United's manager is not putting a timescale on his comeback.
"He had a reaction the other day when he was training," said Benitez. "We will see how he progresses."
Benitez has midfielder Jack Colback back from a two-game suspension, while defender Paul Dummett is expected to return to the starting XI.