WALES have been urged to keep their cool in the red-hot Cardiff atmosphere of today's Six Nations showdown with England to prevent the champions from sticking the boot in.

The two title hopefuls clash at Principality Stadium and will be relishing finally getting under way at 4.50pm after the traditional week of theatrical and occasionally tedious build-up.

England, Grand Slam champions in 2016 and on a 15-Test winning streak, start as slight favourites but Wales are buoyed by a professional win in Italy and autumn successes against Argentina, Japan and South Africa at Principality Stadium.

Everything points to a nip and tuck encounter and Wales defence coach Shaun Edwards knows that discipline will be key given that infringements within range are almost certain to be punished with three points from the unerring boots of Leigh Halfpenny and Owen Farrell.

"The big thing for us, and the big thing that Rob (Howley, head coach) really drives, and he drove it a lot in 2013 when we won the Championship, is discipline," said Edwards.

"We are down to seven penalties a game in the last five games and that's massive with the standard of goal kickers that are going to be on that pitch.

"Owen Farrell and Elliot Daly kicking them from the halfway line while obviously our kickers are not bad in Leigh Halfpenny and Dan Biggar, so discipline is a massive part of the game.

"A big part of who is going to win this Six Nations is keeping 15 player on the pitch. We did that against Italy, our discipline was excellent and that is vital."

Edwards wants Wales to be squeaky clean in defence while forwards coach Robin McBryde hopes to get on the right side of French official Jerome Garces at the scrum.

The props have been changed from Rome with Rob Evans and Tomas Francis getting starts after powerful performances off the bench.

"I thought we scrummaged very well last week," said added. "Our dominance grew as the game wore on. We've worked hard on our reputation as a scrummaging unit, and we will rely on that.

"That's the challenge for the two (props) that are starting on, that they start off in the same vein and don't hold anything back because we know we've got two good scrummagers on the bench as well.

"Across the board, they (Wales forwards) all offer something with ball in hand as well.

"I know there is lot of talk with regards to the ball-carrying abilities of the English pack, but I think the Welsh pack have got equally a number of effective ball-carriers amidst them as well."

Alex Cuthbert is on standby to start if wing George North fails to overcome the injury he sustained to his right leg in Italy.