A number of Wales stars will be missing when the Guinness Pro12 season kicks off this weekend as dual contract rules start to bite.

Alun Wyn Jones, Dan Biggar, Rhys Webb, Scott Baldwin, Jonathan Davies, Jake Ball, Samson Lee and skipper Sam Warburton could all be absent when the tournament starts.

There are 16 players currently signed up with deals jointly funded by the Welsh Rugby Union and the regions. They are restricted to playing a total of only 16 matches in Europe and the Pro12.

It means that despite the fanfare and live TV cameras when the season returns on Friday night, the Ospreys – who host Zebre – will be under-powered.

Jones and Biggar have yet to play in the Ospreys’ pre-season friendlies and assistant coach Gruff Rees said: “People like Biggs and Alun Wyn certainly won’t be for a couple of weeks or so. But for the most part it’s around having a chat about individuals.

“It’s about looking not just at the here and now, but also considering the player first and taking into account the calendar that’s been and the calendar that’s ahead, because it’s another unforgiving 10 or 11 months of rugby.

“We will keep building them up so they get the same amount of training as others had early on in pre-season.

“We have to look down the line for these boys. It’s about protecting the players and getting the best out of them for the Ospreys and to support them for the national game and during what is going to be a big season for them.”

Both Davies and Ball missed the Scarlets’ most recent friendly against Bath and could be held back for their opening game at home to Munster on Saturday.

The Cardiff Blues and the Newport Gwent Dragons only have two dual contract players – Warburton and Gareth Anscombe at the Arms Park, with Hallam Amos and Tyler Morgan at Rodney Parade.

Last season’s World Cup meant the pressure on contracted players to play only 16 matches was not so intense after they missed the opening three months of the season.