Biggar starts at fly-half at the Aviva Stadium after recovering from a spell on the sidelines following a shoulder injury suffered on duty with the Ospreys.
The 28-year-old was hit hard by Fritz Lee of Clermont Auvergne in January and was expected to miss the first three rounds of this year’s Championship.
In the end Biggar sat out only the games with Scotland and England.
“I’ve been in an oxygen chamber to speed up recovery and just working with the physio,” Biggar said.
“The medical staff here have been top draw, together with the conditioning guys.
“It’s more testament to them as it’s easy for me to come in and rehab with the end goal for me to get back in the team and back on the field.
“I’ve been doing a lot of running with the conditioning staff so I’d like to think fitness won’t be an issue on Saturday.
“In the early stages, I did 10 days on the bounce in the oxygen chamber.
“You sit there for hours and hours, with a mask on and it is monotonous day-in, day-out. I finished off the box set of Suits on my iPad. That got me through it.”
Biggar will win his 61st Wales cap in Dublin and will go head-to-head with Ireland’s Johnny Sexton, a man he toured New Zealand with as part of last summer’s British & Irish Lions squad.
“Johnny is an absolutely fantastic player, you can see how important he is for Ireland and Leinster,” Biggar said.
“He is a vital cog, along with Conor Murray, so we know we are up against two of the best in the business. And I like Johnny a lot. He has that streak in him where he knows exactly what he wants.
“He dictates play and in the summer he was really good, you could pick his brain.
“He’s got a great work ethic too and he’s very similar to myself in terms of personality – he has a real drive and will to win.”
Biggar is acutely aware of the importance of this weekend.
Wales know victory is essential if they are to keep their title hopes alive. To do so would also end Ireland’s Grand Slam dream.
“Any Six Nations match is extremely special anyway, but when you play a top team like Ireland away from home, we know it’s almost like a cup final for us,” Biggar said.
“If you lose it’s going to be very difficult to finish on top in the tournament – but if you win, you’ve got two home games to come against Italy and France and you have set yourself up incredibly well.
“That’s the biggest carrot for us. We need to make sure we enjoy the occasion as well. I have been involved in a lot of big games where you go out and you just don’t want to make a mistake.
“You’re uptight and tense and one of the good things about the group we’ve got at the minute is we’ve got a lot of boys in the squad who won’t feel like that.
“They’ll look at it as just another game and that’s how we need to approach it.”
