Wales\' preparations for the Six Nations were rocked on Tuesday when it was revealed that Scarlets fly-half Rhys Priestland will miss the rest of the season after snapping his Achilles tendon. The 25-year-old, who has 22 caps, sustained the injury in a European Cup game against Exeter on Saturday. As well as missing the Six Nations early next year, Priestland faces a fight to regain fitness in time for the British and Irish Lions\' tour of Australia in June and July. Scarlets head coach Simon Easterby revealed that Priestland had undergone surgery on his left Achilles tendon on Tuesday morning. \"It\'s a big blow for Rhys and for our region to lose a player of his quality and influence in our team,\" Easterby said. \"He was coming through well in the last couple of (Wales) games of the autumn, put in a strong performance against Australia and was making a real impact on our game against Exeter, so it is very difficult for him to take. \"But he will get plenty of support from here throughout the injury period.\" The Scarlets\' chief medical officer, Andy Walker, said the surgery was \"non-invasive\" and that Priestland would probably need \"around six months\" to recover. Wales\' end-of-year programme was hampered by injury problems and saw them lose in four straight games to Argentina, Samoa, New Zealand and Australia. Priestland\'s absence for Wales\' Six Nations title defence is a fresh headache for coach Rob Howley, who is in charge of the team on a temporary basis while head coach Warren Gatland oversees preparations for the Lions tour. Prop Aaron Jarvis (knee) has already been ruled out of the Six Nations, while lock Alun-Wyn Jones (shoulder) and flanker Dan Lydiate (ankle) will not be able to participate fully. Full-back Leigh Halfpenny (neck) and centre Jamie Roberts (elbow) are also short of fitness ahead of the tournament, which Wales open with a home game against Ireland in Cardiff on February 2. Priestland was a key performer in Wales\' run to last year\'s World Cup semi-finals in New Zealand and he also played a pivotal role as they claimed a Grand Slam triumph in the Six Nations earlier this year. His form dipped towards the end of the year but he started three of Wales\' end-of-year matches and also made a substitute appearance against the Samoans.