Wales coach Wayne Pivac will name his first Six Nations squad at 11am on Wednesday morning.

He will have spent the past few days putting the finishing touches to the group of players charged with embarking on the defence of the Grand Slam.

We don’t know exactly how many will be in the squad, but the expectation is it will be around 35, which was the number Pivac went for ahead of the Barbarians game in November.

So who will he go for? What does he have up his sleeve? Will there be any surprises?

Rugby correspondent Simon Thomas looks at the options position by position and picks out the men who are certain to be on board and those vying for the remaining spots.

BACK THREE

This is one of a couple of areas where Pivac is really spoiled for choice, with a number of players in a rich vein of form.

He went for seven back three men in his Barbarians squad and if he replicates that it increases the chances of finding a place for teenage sensation Louis Rees-Zammit.

Liam Williams will come back in as he is close to completing his recovery from the ankle surgery which has kept him sidelined since late October.

It remains to be seen whether Josh Adams or George North may be employed as a centre given the injury issues in that area, while Hallam Amos will be unavailable for the first couple of matches, having suffered ankle ligament damage in training last week.

Amos' injury could make the inclusion of Rees-Zammit all the more likely again, with the 18-year-old winger's form for Gloucester pretty irresistible.

Certainties: Leigh Halfpenny, Liam Williams, Josh Adams, Johnny McNicholl, George North

Contenders: Owen Lane, Hallam Amos, Steff Evans, Louis Rees-Zammit, Ashton Hewitt

CENTRES

The problem position.

Jonathan Davies and Willis Halaholo are out for the season, Owen Watkin is set to miss the opening couple of rounds of the Six Nations and Scott Williams is sidelined again.

You would expect Watkin to be included in the squad alongside the one fit starter from the past year, Hadleigh Parkes, but after that it’s a bit of a head scratcher.

All of which makes Owen Williams’ return to action particularly time. It was just his second appearance after nine months out with serious knee damage on the weekend, but he increasingly grew into the game for Gloucester against Montpellier.

Owen Williams makes a break for Gloucester against Montpellier at the weekend

He came on at fly-half after Danny Cipriani’s early departure, but he’s equally adept at inside centre and his distribution, decision-making and running in broken play was pretty impressive given how long he’s been out.

Cardiff Blues youngster Ben Thomas is another option as a midfield playmaker, while the vastly experienced Scott Williams remains a clear candidate depending on his fitness.

Certainties: Hadleigh Parkes, Owen Watkin

Contenders: Scott Williams, Owen Williams, Ben Thomas, Steff Hughes

FLY-HALF

Dan Biggar was unavailable for the Barbarians game through being based in England, but he walks back into the squad given his form at Northampton where he is really flourishing and broadening his attacking game.

He also offers control, astute tactical kicking and mastery of the air, while Jarrod Evans provides a different kind of option with his jinking and instinctive desire to keep ball-in-hand.

Hopefully, Evans will receive the all-clear having sat out Cardiff Blues’ trip to Leicester having failed a HIA after taking a knock against the Scarlets the previous weekend.

If Pivac decides to have three players cover the fly-half berth, Sam Davies would be a frontrunner, having been recalled for the Baa-Baas game, while the versatile Owen Williams is another option.

The real wild card move would be to name Bristol’s Cardiffian Callum Sheedy, who is not tied to England, with his outing for them last year having come in an uncapped match.

Certainties: Dan Biggar, Jarrod Evans

Contenders: Sam Davies, Owen Williams, Callum Sheedy

SCRUM-HALF

The surprise decision by the WRU to allow the Ospreys-bound Rhys Webb to play in the Six Nations has added an intriguing dimension to this position.

Webb hasn’t played much of late, amid Toulon’s displeasure at events, and there are other contenders in good form.

But with the Union having taken the unprecedented step of handing him special dispensation, you would expect him to be on board.

And a trio of Davies, Williams and Webb would be some scrum-half roster to go into the Championship with.

Certainties: Gareth Davies, Tomos Williams

Contenders: Rhys Webb, Aled Davies, Rhodri Williams, Kieran Hardy

FRONT ROW

The propping permutations are difficult to nail down, with it looking like three from four at both loosehead and tighthead.

Rhys Carre will be hoping his sending off against the Ospreys doesn’t harm his Six Nations prospects, with a ban potentially on the cards and Rob Evans and Nicky Smith also vying to join World Cup starter Wyn Jones in the squad.

At tighthead, the return to action of Dillon Lewis is a boost with Tomas Francis out for the whole championship due to shoulder surgery which has created a squad vacancy which could open the way for another English-based player, in the sizeable shape of WillGriff John.

Certainties: Wyn Jones, Ken Owens, Elliot Dee, Dillon Lewis

Contenders: Rob Evans, Nicky Smith, Rhys Carre, Ryan Elias, Leon Brown, Samson Lee, WillGriff John

SECOND ROW

Pivac included both Bradley Davies and Seb Davies in his squad for the Barbarians game, but they could well miss out now with skipper Alun Wyn Jones and Cory Hill having both returned from injury.

Hill has mainly been lining up on the blindside flank for the Dragons since his return from ten months out, so he could offer back-five match-day cover, as could Aaron Shingler, who was utilised at lock a fair bit at the World Cup.

Certainties: Alun Wyn Jones, Jake Ball, Adam Beard, Cory Hill

Contenders: Bradley Davies, Seb Davies

BACK ROW

This is the other area where Pivac has a luxury of riches at his disposal.

That’s often been the case in the back row in recent years, particularly on the flanks.

But now it’s across the board, with the welcome return of Taulupe Faletau providing real depth at No 8, where both Ross Moriarty and Aaron Wainwright are also quality options.

Taulupe Faletau back in action for Bath

Pivac selected no fewer than seven back rowers in his squad for the Barbarians game.

If he goes down that road once more, it would leave scope for at least one of the new kids on the block - Griffith, Lewis-Hughes and Basham - to get the call, while Thomas Young is also back and putting his hand up again for Wasps.

One slight concern is the foot ligament injury to Justin Tipuric, who could be a key man under the new regime with the apparent desire to play a wider game, which would fully exploit his handling skills and support play.

Certainties: Taulupe Faletau, Josh Navidi, Justin Tipuric, Aaron Wainwright

Contenders: Ross Moriarty, Aaron Shingler, Ollie Griffiths, Shane Lewis-Hughes, Taine Basham, Thomas Young

Potential Wales squad:

Backs: Leigh Halfpenny, Liam Williams, Josh Adams, Johnny McNicholl, George North, Owen Lane, Louis Rees-Zammit, Hadleigh Parkes, Owen Watkin, Scott Williams, Owen Williams, Dan Biggar, Jarrod Evans, Gareth Davies, Tomos Williams, Rhys Webb

Forwards: Wyn Jones, Rob Evans, Rhys Carre, Ken Owens, Elliot Dee, Ryan Elias, Dillon Lewis, Leon Brown, WillGriff John, Alun Wyn Jones, Jake Ball, Adam Beard, Cory Hill, Josh Navidi, Aaron Shingler, Aaron Wainwright, Taulupe Faletau, Ross Moriarty, Justin Tipuric