Wales and Scarlets scrum-half Tavis Knoyle will be out of action for the next three months due to a shoulder injury.
Knoyle will have an operation early in the new year which will rule him out of the opening weeks of the Six Nations.
The Scarlets say the procedure will strengthen and stabilise his shoulder joint.
The 21-year-old, who joined the Scarlets in 2009, was a member of Wales' World Cup squad.
Knoyle featured in one game in New Zealand, the 81-7 pool victory over Namibia in New Plymouth.
The former Neath player has been restricted to two starts and three appearances off the bench for the Scarlets this season.
Knoyle's injury is the latest injury blow for Wales ahead of the Six Nations opener against Ireland in Dublin on 5 February.
It was feared the Ospreys player would miss the entire Six Nations campaign but he could return for Wales' trip to England on 25 February.
Roberts will have a scan to determine the severity of the knee injury he suffered in Cardiff Blues' 28-9 Pro12 win over Newport Gwent Dragons on Friday, 23 December.
And the Ospreys' medical team are assessing the fitness of tight-head prop Jones, who was forced off the field during his side's Boxing Day defeat against the Scarlets.