Brentford boss Thomas Frank admits Aaron Hickey has suffered a setback in his injury recovery.
Hickey is working his way back from a hamstring injury.
“Unfortunately, he had a minor setback," Frank said. “I don't know a return date."
On whether he'll make the Euros, he added: “That I don't know. I hope, but sometimes when players have been out for a while I like to see them back on the grass before I comment an estimated guess on what is possible or not.
"He had an operation to his hamstring."