Kyle Sinckler is an ’emotional time-bomb’ that could explode in Cardiff, according to Warren Gatland.

And the Wales head coach was deeply critical of England’s preparations for the Six Nations match – warning Eddie Jones his side may be stuck behind every tractor in Wales as they travel over during rush-hour traffic on Friday.

Gatland worked with Sinckler at close quarters having picked him in all three of his Lions Test sides on the tour to New Zealand two years ago.

Warren Gatland has labelled England prop Kyle Sinckler an ’emotional time-bomb’

So he is aware that while the 25-year-old Harlequins tight-head is a top talent, he can be riled.

‘There’s no doubt he’s a very good players in terms of his carrying, scrummaging and work-rate,’ said Gatland.

‘But there is a challenge with his temperament. He’s aware of it. Other players are aware of it. We’ve already seen in the Six Nations he’s been involved in a couple of incidents.

‘Hopefully we don’t get dragged into that. Emotionally, he can be a bit of a time-bomb. I’m not saying anything that people aren’t aware of.

‘Look, we won’t be going out there trying to antagonise him because that’s not in our make-up. We’ll just go out there and play.

‘Hopefully he goes out and has a good game and keeps his emotions in control because that’s a big challenge for him.’  

Gatland coached the prop during the 2017 British & Irish Lions tour to New Zealand

As in 2017 England have opted against taking part in the traditional ‘captain’s run’ training session at the Principality Stadium Friday lunchtime. 

They are holding a press conference at their Surrey base on Friday morning before travelling across the Severn Bridge.

‘England are making a significant mistake by travelling ton Friday,’ added Gatland.

‘Coming through Newport at about 5pm probably isn’t the best thing to do – going through the Brynglas tunnel.

‘There’s a good chance there’ll be tractors and buses holding them up! So that will be an experience for them.’

Jones, however, is happy with England’s arrangements: ‘It’s the pattern we’re getting into,’ he said.

‘We’ve got other things in mind for the way we’re preparing for the Six Nations while specifically we want to win the Six Nations and we want to win on Saturday, we’re looking at how we do things in the future.’ 

England have requested that the roof of the Principality Stadium remains open for the clash

As revealed by Sportsmail on Thursday England requested for the Principality Stadium roof to be left open for the match.

Wales always want the roof to be closed, but under Six Nations regulations the away side has discretion.

And Sportsmail understands England’s request came through Thursday lunchtime during Gatland’s press conference.

The last time it was shut for a Six Nations Wales v England match was when England lost 30-3 in 2013.

England have lost four of five Tests when the roof is closed but won five of six when it is open.

According to Sportsmail’s research Wales’s win percentage meanwhile drops from 61 per cent for home games with the roof closed to 52 per cent when it is left open.

Gatland wishes it could be closed permanently in the Championship – as it is for all other Wales home games.

‘It’s a bugbear of mine that we can’t decide in the Six Nations whether we can close the roof on our own stadium,’ he said.

‘I’d be going to the Six Nations and banging my fists on the table – saying “it’s our roof, we should be able to make the decision”.

‘It’s out of our hands, though, and we have to abide by the rules.’