Ulster’s Pro12 hopes have been hit with the news that Nick Williams requires surgery on his injured shoulder and will be out for the rest of this season.

Powerful number eight Williams is due to leave Belfast at the end of the current campaign and join Cardiff so it looks as though he has played his last game for the province.

He suffered the shoulder injury during the defeat to Glasgow in March and attempts to rehabilitate the problem have been unsuccessful, meaning he must now go under the knife.

Ulster are currently in fourth place in the table, the last of the play-off spots, and have Scarlets snapping at their heels.

Ulster take on league leaders Leinster in a big Irish derby at Kinspan Stadium on Sunday.

Ireland wing Tommy Bowe will also miss that game having suffered a mild knee reaction during the recent game against Zebre.

In other Ulster injury news, Wiehahn Herbst has begun to reintegrate into team training sessions and the medical team is confident that he will be available for selection within the next two weeks.

Both Louis Ludik and Paul Rowley remain unavailable for selection as they continue to rehab their respective groin and knee injuries.

Ian Humphreys has seen a spinal specialist and had a recent injection for his ongoing back injury, which he will continue to rehab.

Alan O'Connor had surgery ten days ago following his recent shoulder dislocation. He is expected to be fit for the beginning of next season.

Ruaidhri Murphy also had recent surgery for a finger injury and he won't play again this season.

Sammy Arnold is continuing to rehab his hamstring injury but he too is unlikely to be available for the remainder of the campaign.