Warren Gatland has warned his Wales side against complacency ahead of their World Cup quarter-final with Six Nations rivals Ireland on Saturday.
But coach Gatland said: "We are under no illusion that Fiji made 10 changes so we'll not get too carried away."
And captain Sam Warburton added: "There is still a lot of work to be done."
Wales qualified for the knockout stages in New Zealand as runners-up to defending champions South Africa in Pool D, a one-point defeat by the Springboks followed by the wins over Samoa, Namibia and Fiji.
The Irish go into the Celtic clash having won Pool C with a 100% record, including a surprise win over pre-tournament favourites Australia.
Gatland, who coached Ireland between 1998 and 2001, said he was excited that northern hemisphere sides are one side of the knockout draw with southern hemisphere sides on the other.
And Wales skills coach Rob Howley admits there is "history" between Wales and Ireland as the 2008 Grand Slam champions prepare to take on the 2009 Grand Slam champions, in Wellington.
"We'll all have to agree that so far in this World Cup, the performance of these two nations have been impressive," said Gatland.
"We've stepped up a little bit and so have Ireland in terms of representing the northern hemisphere, and hopefully we can continue to go a bit further."
The winners of Saturday's showdown will face either England or France in Auckland on 15 October and Howley admits Ireland will be "tough".
"There's a lot of history between Wales and Ireland," he said.
"They have qualities and world-class players but it is going to be tough to call. On the day, Ireland can beat us and we can beat them.
"Some people might say we have achieved something getting to a quarter-final and coming out of the pool of death.
"But I know we have an ambitious and quality group of players."
Back-rower Warburton has impressed in New Zealand and the Wales skipper insists his side are not happy just reaching the last eight.
"We don't want to get ahead of ourselves," said Warburton.
"The last two games we have overplayed a bit, and had a few handling errors and balls going down through maybe trying a bit too hard, so there are a few creases we need to iron out."
"Both players know each other as a lot of were in involved with the British and Irish Lions in 2009," added Warburton.
"That makes it more exciting for players.
"Ireland have great players and everyone knows they have that one big performance in them so we must be switched on.
"But we must believe we can beat anyone now."
WALES 2011 RUGBY WORLD CUP SQUAD
Props: Ryan Bevington, Adam Jones, Paul James (all Ospreys), Gethin Jenkins (Blues), Craig Mitchell (Exeter), Hookers: Huw Bennett (Ospreys), Lloyd Burns (Dragons), Ken Owens (Scarlets). Locks: Luke Charteris (Dragons), Bradley Davies (Blues), Alun Wyn Jones (Ospreys). Back-rows: Toby Faletau (Dragons), Ryan Jones (Ospreys), Danny Lydiate (Dragons), Andy Powell (Sale Sharks), Sam Warburton (Blues, capt).
Full-backs/wings: Lee Byrne (Clermont Auvergne), Aled Brew (Dragons), Leigh Halfpenny (Blues), George North (Scarlets), Shane Williams (Ospreys). Centres: Jonathan Davies (Scarlets), Jamie Roberts (Blues),Scott Williams (Scarlets). Fly-halves: James Hook (Perpignan), Stephen Jones, Rhys Priestland (both Scarlets), Scrum-halves: Tavis Knoyle (Scarlets), Michael Phillips (Bayonne), Lloyd Williams (Blues).