The Six Nations returns with a bang this weekend as Wales host England in a mouthwatering clash at Cardiff’s Principality Stadium.

Here, Sportsmail looks at the key questions ahead of the big game.

What is on the line?

The Six Nations championship. Both sides are two wins from two so whoever triumphs here will be very hard to stop from going on to lift the trophy on March 16. England have already beaten pre-tournament favourites Ireland on their own patch so would be nailed on for a Grand Slam with a win in Cardiff but if Wales win that opens the door for Ireland again, who travel to Cardiff on the final day.

Looking longer term, the World Cup kicks off in September and whoever wins here will get a massive psychological boost from the result should the two meet in Japan.

England head coach Eddie Jones (left) and his Wales counterpart Warren Gatland (right)

Who are the favourites?

England. Not massively, but they are expected to win. Eddie Jones’ side sent shockwaves through the sport by swatting Ireland aside but home advantage is a big leveller for Wales who are on a record-breaking 11-match winning run, so victory for them would not be a shock. Either way, it should be tight.

What are the key battles?

Openside flanker – Justin Tipuric v Tom Curry: England’s breakdown problems have dogged them since Stuart Lancaster’s reign but they finally appear to be solved with the emergence of Curry and his rival for the No 7 shirt Sam Underhill. Curry was excellent against Ireland but comes up against a world class openside in Tipuric. 

Hooker – Ken Owens v Jamie George: Wales coach Warren Gatland picked George over Owens for the Lions but there is little to choose between the two hookers. With England’s firepower out wide the Wales lineout and scrum will have to be superb to win it and Owens’ performance will be vital to both.

Fly-half – Gareth Anscombe v Owen Farrell: If England can achieve parity up front the presence of Farrell and the flyers outside him should be too much for Wales. Anscombe has a massive task on his hands to match Farrell from the tee having been preferred to Dan Biggar and with regular kicker Leigh Halfpenny out of action.

England captain and fly-half Owen Farrell has started the Six Nations in blistering form

Do the coaches get on?

No – well, certainly not in public. Both Antipodeans love playing mind games in the build-up to a big match and this game has been no different. Jones has adopted a mocking tone describing Wales as ‘potentially the greatest team ever’ and New Zealander Gatland will be desperate to win in his final Six Nations game against the Australian having lost the previous three – never by more than six points. 

Will the Principality Stadium roof be open or shut? Does it make difference?

The roof will be open and Gatland certainly thinks it makes a difference. He said this week: ‘It’s a bugbear of mine… it’s ironic that it’s our stadium and we can’t decide what we do with it.’

Six Nations rulemakers decided in … that having the roof closed gave Wales an advantage so have allowed the away team to choose ever since and England have unsurprisingly opted for it to remain open, theoretically dampening to atmosphere.

Chelsea have been given a two transfer window ban by FIFA for breaching the rules around the transfer of minors — and it could see Eden Hazard stay at Stamford Bridge. 

The west London club have been found to have breached article 19 of FIFA’s regulations with regards to the transfer of 29 minor players and article 18 regarding two further minors. 

They have now been banned from registering new players for the next two transfer windows — the coming summer window and next January. But Sportsmail understands they have been prepared for this eventuality for a while.

Chelsea have been given a two transfer window ban for breaching FIFA regulations

The decision could impact on Eden Hazard’s future and stop him leaving for Real Madrid

They are likely to appeal to FIFA and the Court of Arbitration for Sport. That means they will almost certainly be able to get the ban pushed back until after the summer window, in order to do any key business.  

They have also been fined 600,000 Swiss Francs (£460,314).  The FA have been found to have breached the rules in connection with minors too and have been fined 510,000 Swiss Francs (£391,260) — they have announced they will be appealing that decision.

Chelsea will now be desperate to keep hold of Hazard despite the serious interest from Real Madrid. The Belgian is a long-term target for Real but with Chelsea limited when it comes to signing replacements, he may have to stay.

Callum Hudson-Odoi may also struggle to move to Bayern Munich, while Ruben Loftus-Cheek could have to stay at Stamford Bridge.  

It could also limit Callum Hudson-Odoi’s ability to leave the club for Bayern Munich

Maurizio Sarri is already under pressure and this will limit his ability to change the side

The signing of Bertrand Traore in 2014 sparked the investigation into their business. This took place over three years, from 2015.

They are thought to have signed Traore before his 18th birthday, and have provided misleading information as to when he was signed.

Chelsea paid his mother £155,000 in 2011 to take a first refusal option on him and then £13,000 to the club chaired by his mother, AJE Bobo-Dioulasso.

Traore was sold to French side Lyon in June 2017 for £8.8million, having played a total of 16 games for Chelsea.

A FIFA statement read: ‘The FIFA Disciplinary Committee has sanctioned the English club Chelsea FC and The Football Association for breaches relating to the international transfer and registration of players under the age of 18.

Owner Roman Abramovich attending a performance of the Nutcracker in Moscow on Tuesday

‘Chelsea was found to have breached art. 19 of the Regulations in the case of twenty-nine (29) minor players and to have committed several other infringements relating to registration requirements for players. 

‘The club also breached art. 18bis of the Regulations in connection with two agreements it concluded concerning minors and which allowed it to influence other clubs in transfer-related matters.

‘The Disciplinary Committee sanctioned Chelsea with a ban on registering new players at both national and international level for the next two (2) complete and consecutive registration periods. 

‘This ban applies to the club as a whole – with the exception of the women’s and futsal teams – and does not prevent the release of players. Additionally, the club was fined CHF 600,000 and given a period of 90 days to regularise the situation of the minor players concerned.

‘The Football Association was also found to have breached the rules in connection with minors.  

The signing of Bertrand Traore in 2014 sparked the investigation into their business

‘It was fined CHF 510,000 and given a period of six months to address the situation concerning the international transfer and first registration of minors in football. 

‘The protection of minors is a key element in FIFA’s overall regulatory framework relating to the transfer of players and effective enforcement of these rules is paramount, as also confirmed on various occasions by the Court of Arbitration for Sport.

‘The decisions issued by the Disciplinary Committee were notified today and can be contested before the FIFA Appeal Committee.’

Traore joined Ligue 1 side Lyon in summer 2017 for £8.8million after 16 games for Chelsea

An FA spokesperson revealed they would be appealing FIFA’s decision to fine them: ‘The FA notes the decision of the FIFA Disciplinary Committee published today. The FA has cooperated fully with FIFA’s investigations, although we have raised some concerns with FIFA regarding its disciplinary processes.

‘The FA intends to appeal the decision. We will however continue to work with FIFA and Chelsea in a constructive manner to address the issues which are raised by this case.

‘As this is an ongoing legal process it would not be appropriate to comment further at this time.’