Cardiff back row Josh Navidi is set to miss the Six Nations after having shoulder surgery.
The 30-year-old is expected to be on the sidelines for five months with his latest injury.
The Bulls game was 28-cap Navidi's first of the season after he had been on the British and Irish Lions' tour of South Africa earlier this year.
Navidi saw a specialist on Tuesday to discover the extent of the injury and has had an operation to fix the issue with a comeback date of late March or early April next year.
Wales begin the defence of their Six Nations title next year in Ireland on 5 February and finish at home against Italy on 19 March.
Wales, who start their autumn series against New Zealand on 30 October, already have a host of players missing through injury.
Justin Tipuric, George North, Dan Lydiate and Leigh Halfpenny have been ruled out of the entire autumn, while Cardiff flanker James Botham is also set to miss the games against New Zealand, South Africa, Fiji and Australia at the Principality Stadium in Cardiff.
Navidi's absence means four Lions back rowers will be unavailable to face New Zealand with Tipuric, Lydiate and Taulupe Faletau also missing against New Zealand, while Scarlets' uncapped flanker Josh Macleod is also sidelined.
Dragons trio Ross Moriarty, Aaron Wainwright and Taine Basham will be in contention to face the All Blacks.
Cardiff flanker Ellis Jenkins has also been named in the autumn squad although he gave Pivac a late concern by coming off against Sharks on 16 October with a rib problem.
Wasps flanker Thomas Young will join Cardiff next season and has been included in Pivac's squad despite the fact that he will be playing outside Wales for the rest of the regular campaign.
The 29-year-old has been given special dispensation to feature despite the Welsh Rugby Union's (WRU) 60-cap rule because of the flanker injury crisis.
The WRU introduced a senior player selection policy (SPSP) in 2017 that deemed a player representing a club outside Wales and with fewer than 60 international caps would be ineligible for the national side.
Young and fellow England-based players Dan Biggar, Callum Sheedy, Louis Rees-Zammit, Faletau, Nick Tompkins and Christ Tshiunza are not available against the All Blacks because the game falls outside World Rugby's international window.
Scarlets full-back Liam Williams is also a doubt to play against New Zealand after having had his appendix removed.