The 23-year-old will be expected to pull the strings after being picked ahead of Hook, who at 27 has been an established part of the Welsh set up for the past six years and is currently the nation's third highest points scorer of all time.
But Biggar sees no reason why his relative lack of experience should hinder his ability to stamp his authority on the Championship.
"There's a lot of pressure, it is part of the job title. It's a difficult position to be in," said Biggar.
"So I could give you the routine answer of you just get on with it and you don't pay any attention to it, but of course you do.
"You are aware of the Welsh 10 jersey and the expectation around it. As a player, when your team is playing well, it's a great position to be in, but when things aren't going quite as well as you would perhaps have liked, that's when you come under scrutiny.
"As a 10, especially in Wales, that's part and parcel of the job. You have to take it as it comes, but you also have to enjoy the high bits as well, when you are playing well and winning."
Despite his 12 caps so far for his country Biggar has yet to feature in the RBS 6 Nations, a fact that is not lost on the fly-half who is desperate to lay down a marker moving forward.
"I don't think there is any hiding my international career has been a bit stop-start and I hope to get it going this weekend against a good Irish side," he added.
"The Six Nations tournament is the best in the world, in my opinion, and it's something I'm really looking forward to.
"I would like to think it's my best opportunity to put a marker down and go from there.
"It's the opening match of the campaign and, more importantly, we, as a team, want to get off to a good start."