Video: Wales can’t expect miracles from debutant Biggar, says boss Rob Howley
"Dan Biggar is the in-form 10 in Wales," said Howley, after selecting him ahead of James Hook to replace an injured Rhys Priestland.
"It is important he gets an opportunity, but please can you keep the pressure off him. It is important he is given the chance to develop.
"It's a big game for Dan. Obviously, he understands that, but our Welsh culture and the way we talk about our 10s, it is important that Dan is given an opportunity.
"He will certainly be given a chance by the Wales management. He understands there is competition with James, but it is a big starting game for Dan. He has been exceptional this week."
Biggar will line up in a team containing 10 survivors from the side that launched last season's Six Nations title and Grand Slam-winning campaign by beating Ireland.
But while familiar faces like Leigh Halfpenny, Jamie Roberts, Mike Phillips, Adam Jones and skipper Sam Warburton all feature, there is a Wales debut for 28-year-old Newport Gwent Dragons lock Andrew Coombs.
Coombs' elevation to Test match status comes less than three years after he made his Dragons debut, and he only recently switched positions from back-row to lock when the Dragons were hit by injuries.
The former computer software salesman played Welsh Premiership club rugby with Pontypool and Newport before graduating into the Dragons' professional ranks.
But both Warburton and Howley have been vastly impressed by him, despite his relative lack of experience at regional level.
"You can tell he (Coombs) is dying to get on the pitch," Warburton said.
"I think he is one of those players who I don't think it will affect him too much. I think he will take it all in his stride.
"He seems very confident and ready for the game on Saturday. He is a very difficult player to play against, and he has played exceptionally well over the past few months. I am looking forward to packing down with him."
And Howley said: "Andrew has been on our radar over the last six months, really. He's a very good ball-carrier, his work-rate is second to none and he is excellent in the lineout.
"The lineout game against Ireland is always important. When we've played against them recently there has always been a number of lineouts in the game. We just need to have options in that area, and Andrew will certainly add to that part of the game."
Coombs will partner fit-again Ian Evans at lock - knee trouble has meant Evans not playing since November - but Wales remain without injured second-rows Alun- Wyn Jones, Bradley Davies and Luke Charteris.
Howley has resisted any temptation to field two openside flankers - Warburton and Justin Tipuric - with Warburton retained in his familiar number seven shirt, Aaron Shingler filling blindside duties and Tipuric on bench duty.
Former Wales captain Ryan Jones, who would have offered a back-row or second-row option, is sidelined after dislocating his thumb during the Ospreys' Heineken Cup game against Leicester 18 days ago.
Elsewhere, Howley has reunited the 2009 British and Irish Lions Test front row of Gethin Jenkins, who wins his 95th cap, Matthew Rees and Adam Jones, with powerhouse scrummager Jones back in action after missing Wales' entire autumn series this season because of a knee injury.
And there is a role among the replacements for uncapped Harlequins lock Olly Kohn. Born in Bristol, 31-year-old Kohn has Welsh qualification through his late grandfather, who hailed from the Rhymney Valley.