London - Wales coach Warren Gatland has suggested England prop Kyle Sinckler "emotionally, can be a bit of a time bomb" heading into this weekend's crunch Six Nations clash in Cardiff.
Sinckler was involved in an exchange of words with Ireland's Peter O'Mahony during England's opening win in Dublin and last time out received a ticking off from referee Nigel Owens for slapping France forward Arthur Iturria on the head.
England coach Eddie Jones has made it clear he wants his players to keep their cool at the Principality Stadium, where victory for either of the last two unbeaten sides in the Championship could go a long way to deciding the destiny of the title.
Gatland, who coached Harlequins front-row Sinckler on the British and Irish Lions' 2017 tour of New Zealand, said: "I think the thing with Kyle, there is no doubt he's a very good player in terms of his carrying, scrummaging and work-rate.
"There is a challenge sometimes with his temperament. He's aware of it. Other players are aware of it. We've already seen in the Six Nations that he has been involved in a couple of incidents."
The New Zealander added: "Hopefully, we don't get dragged into that on Saturday. Emotionally, he can be a bit of a time-bomb. I am not saying anything that people aren't aware of."
But Gatland insisted: "Look, we won't be going out there trying to antagonise him, because that's not in our make-up. We will just go out there and play."
Meanwhile the experienced Gatland, who will stand down as Wales coach after this year's World Cup in Japan, was all smiles when asked about England counterpart Eddie Jones' comment that Saturday's match would be the biggest in the Wales' players lives.
"He's taking the mick. He's talking about us," said Gatland. "It's a big game, but it's not the biggest game we've played in. It's only against England!"
Saturday's clash kicks off at 18:45 (SA time).
15 Liam Williams, 14 George North, 13 Jonathan Davies, 12 Hadleigh
Parkes, 11 Josh Adams, 10 Gareth Anscombe, 9 Gareth Davies, 8 Ross
Moriarty, 7 Justin Tipuric, 6 Josh Navidi, 5 Alun Wyn Jones (captain), 4
Cory Hill, 3 Tomas Francis, 2 Ken Owens, 1 Rob Evans
16 Elliot Dee, 17 Nicky Smith, 18 Dillon Lewis, 19 Adam Beard, 20 Aaron
Wainwright, 21 Aled Davies, 22 Dan Biggar, 23 Owen Watkin
Elliot Daly, 14 Jack Nowell, 13 Henry Slade, 12 Manu Tuilagi, 11 Jonny
May, 10 Owen Farrell (captain), 9 Ben Youngs, 8 Billy Vunipola, 7 Tom
Curry, 6 Mark Wilson, 5 George Kruis, 4 Courtney Lawes, 3 Kyle Sinckler,
2 Jamie George, 1 Ben Moon
Substitutes: 16 Luke Cowan-Dickie, 17
Ellis Genge, 18 Harry Williams, 19 Joe Launchbury, 20 Brad Shields, 21
Dan Robson, 22 George Ford, 23 Joe Cokanasiga