The Leinster hooker was replaced after 36 minutes of Saturday’s 29-10 win over England. He was seen wearing a protective boot and using crutches after the game.

Sheehan saw a specialist on Tuesday, assistant coach Mike Catt told a news conference in Bayonne, where Ireland meet Samoa in their last World Cup warm-up test on Saturday.

After last weekend’s victory in Dublin, coach Andy Farrell said Sheehan "lost power" in the foot with Catt adding on Tuesday: “He's still being diagnosed so we'll have a much better idea tomorrow or on Thursday in terms of where he's at and when his back to return dates are.”

Ireland are still to announce their World Cup squad but Sheehan’s selection is now in the balance.

"What you get from Dan is one of the best hookers in the world currently so he's going to be missed in whatever team he plays in, but again we've got full faith in Rob Herring (33), Ronan Kelleher (25) and Tom Stewart (22) obviously, who is showing his face at the moment,” Catt added.

"So it gives these guys an opportunity to have a pop this weekend and again, depending on the diagnosis, we'll see how we go on the back end of it.”

Uncapped Munster hooker Diarmuid Barron (25) was called up as cover for Sheehan.

Ireland compete in Pool B at the World Cup and start against Romania in Bordeaux on September 9th.