Wales duo Gethin Jenkins and Martyn Williams will be out of action until November after they both required surgery to repair shoulder injuries sustained on the recent British & Irish Lions tour.
Cardiff Blues prop Jenkins suffered a dislocated shoulder in the second half of the second Test against South Africa, although he played on for some time with the injury and only left the field after breaking his cheekbone.
Forward Williams also suffered with shoulder problems throughout the tour but they were not severe enough to keep him out of action and he played in all three Tests. However, he will have surgery to repair the damage and faces four months on the sidelines.
The news compounds Wales' injury woes as prop Adam Jones has already been ruled out of the autumn Tests, with Australia, New Zealand and Argentina visiting Cardiff.
Wales' acting head coach Rob Howley has given Sam Davies and Rory Thornton a boost ahead of the RBS 6 Nations by naming the uncapped Ospreys duo in his largely experienced squad for the Autumn Internationals.