Wales have been struck by a blow after experienced back-row Ryan Jones was ruled out of their opening two Six Nations matches due to injury.
The Osprey suffered the injury during the region's Heineken Cup defeat to Leinster on Friday. It is not yet clear if he will miss the tournament.
Jones has been replaced by James King.
"Wales have released Ospreys back-row Ryan Jones back to his region due to injury," read a Welsh Rugby Union statement.
"Jones met up with the squad this morning as they began preparations for the forthcoming Six Nations and has been ruled out with a hamstring injury.
"Jones' regional team-mate James King, who made his debut for Wales last summer in Japan, has been called into the squad."
Wales have also added Dragons hooker Sam Parry and Scarlets lock Jake Ball to the squad.