Cardiff - Wales head coach Warren Gatland says nullifying the threat of half-back stars Johnny Sexton and Conor Murray is key to victory in Saturday's Six Nations clash in Dublin.

Gatland, who this week becomes only the second coach after New Zealand World Cup winner Graham Henry to clock up 100 Tests for one country, has made three changes from the side beaten by England, calling up fit-again fullback Leigh Halfpenny, wing Liam Williams and flyhalf Dan Biggar.

The New Zealander, who coached the two Irish players during the British and Irish Lions tour of New Zealand last year, said the key was to attack them.

"We have had some pretty good success not allowing Johnny too much time and space on the ball," he said. "Our line-speed defensively has got to be good.

"We have got to put Conor and his kicking game under pressure. We have to be prepared to be pretty physical against them.

"We have got to be physical against them up front and stop the running power of someone like CJ Stander, and stop allowing Murray and Sexton to dominate the game. If we can do that, we have got a chance."

Many pundits feel the Six Nations is hurtling towards a title showdown between England and Ireland at Twickenham on March 17, with both sides unbeaten after two rounds of the championship.

Asked if he thought Ireland were the strongest team in the tournament, Gatland added: "No. England are a tough outfit. Ireland ground out a win in France.

"You've got to keep your discipline against Ireland. Our discipline has been excellent in the first two games," he said.

"We've got to make sure we don't give Ireland an opportunity to kick to the sidelines by giving away penalties and execute their driving lineout, which is pretty effective, and allow Johnny Sexton to keep their scoreboard ticking over with three points.

"That's what they do. They play through lots of phases, but we've conceded the least points in the competition so far."

Biggar has shaken off a shoulder problem, returning to the starting line-up instead of Rhys Patchell, while Halfpenny has recovered from a foot infection and replaces Gareth Anscombe, with Saracens wing Williams in for Worcester's Josh Adams.

Both Patchell and Adams drop out of the match-day 23, and Northampton wing George North remains on the bench, with Gatland opting for a back-three of Halfpenny, Williams and Steff Evans.