Wales coach Warren Gatland is expected to include several injured leading players when he names his Six Nations squad on Tuesday.
Captain and open-side flanker Sam Warburton, of Cardiff Blues, has not played since November.
Scarlets full-back Liam Williams’ last game was at the 2015 World Cup.
Warburton’s back-row colleague Dan Lydiate last played for Ospreys on New Year’s Day while veteran prop Gethin Jenkins is also a concern
Aged 35 and with a record 119 Wales caps, Jenkins said during the World Cup he hoped to continue his Test career beyond the tournament.
Since Wales’ World Cup quarter-final exit, some of the players who were ruled out before and during the tournament have returned.
Centre Jonathan Davies is back to fitness and form with Clermont Auvergne after recovering from knee surgery.
Utility back Gareth Anscombe played for Cardiff Blues in their European Challenge Cup defeat at Harlequins at the weekend after an ankle problem.
Likewise Newport Gwent Dragons’ back-three player Hallam Amos appeared in their Challenge Cup win over Castres.
Warburton could return in Europe against Calvisano on Friday and/or face Edinburgh in the Pro12 on 30 January.
Full-back Williams could also return on 30 January, against Connacht for Scarlets.
Scrum-half Rhys Webb is due back from his foot injury for Ospreys in February.
Scarlets lock Jake Ball could return from a knee problem towards the end of the tournament
Dragons centre Tyler Morgan is not expected to return from the shoulder injury he suffered during the World Cup until late January.
Wales’ Six Nations campaign begins against Ireland in Dublin on Sunday, 7 February.
Gatland’s side go on to host Scotland on Saturday, 13 February and France on Friday, 26 February.
England will have the chance to avenge their World Cup defeat when they again host Wales at Twickenham on Saturday, 12 March.
Seven days later Wales’ tournament ends against Italy in Cardiff.