The 23-year-old underwent a scan on Monday with fears growing he will miss Wales’ remaining Pool D games against Namibia and Fiji.

The Dragons blindside is no stranger to injury having battled back from a broken neck suffered four years ago against Perpignan in the European Cup.

Lydiate has returned to take his place as one of Wales’ most important players and defence coach Shaun Edwards admits he’s desperate for the flanker to play again in New Zealand.

“Dan is still in a moon boot, but they put moon boots on everything these days,” he said.

“I just hope Dan recovers quickly to continue to make his mark in this World Cup. He’s probably my favourite player – and as a defence coach that says a lot.”

Full-back James Hook is also expected to miss the final pool games after injuring his shoulder but forwards coach Robin McBryde is refusing to put a timescale on the pair’s return.

“Nothing has been decided for sure,” he said. “We're fortunate in that time is on our side.

“We'll see how they react to treatment and give them as much time as possible. It will be wrong of us to rush into any decisions.”