Keane told the club's official website: "It's not the same injury, but it's a similar type of injury in the same area.
"It's a setback for the lad and for us because he's a big player for us.
"It's the downside with hamstring injuries. We look at injuries, we look at players' recovery, but one thing we don't do is push them too much. It's just one of those things.
"He had a week's running with the medical staff and then he trained with us. He was doing okay and then he walked off saying he felt something. It's a blow."