England centre Billy Twelvetrees is working hard on improving his defensive game ahead of facing the threat of Jamie Roberts.
Two notable incidents have raised question marks over Twelvetrees' effectiveness on the other side of the ball over the last five months.
The Gloucester back was at fault against Australia last November for Matt Toomua's try, before missing four tackles in the win over Ireland.
Having though secured the number 12 shirt and built an effective midfield partnership with Luther Burrell, Twelvetrees is looking to tweak the other parts of his game that need work.
"I'm working on it all the time, as the whole team do. It's a huge part of our game," said Twelvetrees.
"We want to put pressure on attacks and make them make errors.
"You have to make your tackles and physically dominate the opposition. There's a huge focus for me to get better at that."
Twelvetrees will face up to the hard-running threat posed by Wales centre Roberts on Sunday, knowing full well that it will be one of his toughest challenges.
"Yes, in terms of physicality Jamie Roberts will be the biggest challenge I have faced," added Twelvetrees.
"He's a top-class player and he's shown that in the years he has played for Wales and for the Lions. He's always making breaks and getting over the gain line.
"He's one of these players you look up to and he's such a good professional as well."
The former Leicester Tigers back is also hoping for a fast start in a fixture that many pundits and bookmakers are struggling to call.
"It's huge for us as a team to get on the front foot straight away," stated Twelvetrees.
"Rugby is a huge mental battle and psychologically you want to get on the front foot straight away and get the game going.
"It's the same with Wales, they're going to know what's coming and so will we.
"But you've still got to deal with it. It's about turning up on the day and performing."