Wales coach Warren Gatland says his side can derail Ireland before the World Cup in Saturday's tournament warm-up match in Cardiff.

Ireland suffered a 57-15 hammering against England last weekend, while Wales are currently ranked number one side in the world.

"I was surprised by the Ireland result against England," said Gatland.

"This is professional sport and we can put a massive dent in their confidence, and derail them a little bit."

Ireland have never excelled in World Cups and have never gone past the quarter-final stage in the tournament.

"They are under an enormous amount of pressure back home with a lot of criticism given that they haven't progressed in World Cups further than they probably would have expected," said Gatland, who coached Ireland between 1998 and 2001.

"They're coming here knowing they've been criticised, they'll be hurting from last week.

"There are a lot of doubts in the coaches' minds about who their best players are.

"Some of their players are getting a bit older, is it a time to put some of the youngsters in? It's a massive game for Ireland that will answer a lot of questions.

"That's why I'm excited. It's a challenge for us."

Gatland also hopes Ireland will still be affected by Wales' 25-7 victory in March in Cardiff which sealed the Grand Slam and Six Nations title for Gatland's side.

"There could also be players involved who played in the Six Nations game and they'll be hurting from that as well," said Gatland.

"I couldn't ask for a better game for this group of players to have to go out there and perform."

'Ridiculous rankings'

Wales will lose their number one ranking if they do not beat Ireland this Saturday and could slip to fourth.

Joe Schmidt's men could even go top if they defeat Gatland's side by more than 15 points.

Current World Rugby vice-president and former Argentina scrum-half Agustin Pichot has criticised the ranking system, calling it ridiculous and said he was going to change the process.

Pichot highlighted that Wales are above New Zealand despite not having beaten the All Blacks since 1953.

Gatland has previously said the ranking was just a number and insisted Wales had not asked for the accolade.

"I'm quite happy to decline the position," said Gatland.

"We from now will forfeit our position. We didn't go in and apply for it. If he's not happy, then take it off us. It doesn't bother us.

"So we officially decline the position - thanks very much."