Martyn Williams has hailed Toby Faletau as the most naturally gifted player he has ever played with as the Wales star prepares for his Six Nations debut.
Flanker Williams won 99 Wales caps and featured on the last three Lions tours.
"He is phenomenal, the most naturally gifted rugby player I have ever played with," he said of the 21-year-old.
"A lot of the time you get great athletes who are not perhaps the most natural rugby players, and vice versa. But he has got the whole package."
Number eight Faletau, 21, whose Tongan father - a former international lock - moved to Wales when Toby was seven, only made his debut in the capped international against the Barbarians last June.
But he forced his way into the World Cup squad during the warm-up Tests and excelled at the tournament in New Zealand, scoring tries against South Africa and Namibia on Wales' run to the semi-finals.
"After he first came into the Wales set-up for the Barbarians game, Toby worked really hard with the conditioning coaches," Williams said.
"He has just been unbelievable since, particularly when you take into account that the World Cup was his first major tournament. Everything comes so easily to him.
"When you see him playing in a sometimes struggling Dragons side, you can imagine what he would do in one of the top teams. But he is the sort of player you can build a franchise around, he is that good.
"He is very quiet but I think he just loves the game of rugby, he loves training, and he has been in outstanding form since the World Cup."
Williams believes Faletau and his fellow back-rowers face a big challenge trying to emulate the game plan that worked so effectively in their quarter-final against the Irish, where they successfully nullified the ball-carrying threat of Sean O'Brien and Stephen Ferris in particular.
"Wales really targeted the Irish back row and did such a good job on their runners - getting them low, cutting them down," Williams said.
"Shaun Edwards is the best defence coach in the world and he will have a plan. But lightning rarely strikes twice and they are going to have to be on their mettle."
Wales will approach Sunday's clash without four of the pack that performed so effectively in Wellington, and Williams says their replacements - Rhys Gill, Bradley Davies, Ian Evans and Ryan Jones - will need to re-produce the same work-rate as their immediate predecessors.
"You can't under-estimate the four players who will be missing from the pack," he added.
"When you take away Gethin Jenkins, Luke Charteris, Alun Wyn Jones and Dan Lydiate, that is four phenomenal engines there who do so much unseen work.
"The boys taking their places need to emulate that. When Wales beat Ireland at the World Cup, the work-rate of the whole pack was phenomenal. They are big losses but I know the Welsh boys are confident.
"There is no reason why they can't sneak a win out there but it is going to be very tough. Ireland are very dangerous when they have a point to prove. We saw when they were hurt what they did to England at the end of last year's Six Nations.
"Their provincial teams are flying in Europe but they are missing Brian O'Driscoll, and you can't under-estimate that - he is one of the best players in the world.
"It is all about who gels best on the day, in the first game. Ideally you'd like to be at home, and Wales haven't got a good record in Dublin, but the younger players don't seem to know or care much about that.
"Our coaching team will have a plan, they will cover every detail, and Wales will be as well prepared as any team."