Wales won their Six Nations opener against Scotland at the beginning of the month but lost 12-6 to England at Twickenham in their last game two weeks ago.
They face an Ireland side on Saturday, who have begun the competition with victories over France and Italy and top the Six Nations table, level on nine points with England, who have also won both their opening matches.
"If we lose it's going to be very difficult to finish on top in the tournament, but if we win, we've got two home games to come against Italy and France and have set ourselves up incredibly well. That's the biggest carrot for us," Biggar told reporters.
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"Ireland are a fantastic side, extremely well coached with a lot of experience in their side in key positions," he added.
"But we have a very good record in Dublin under (coach Warren Gatland). We won the World Cup warmup out there, got a draw there last time and won a couple of years before that. We also won against Ireland at home last year.
"We know it's almost like a cup final for us," Biggar said of Saturday's game.
The British and Irish Lions flyhalf will make his first appearance for Wales in this year's Six Nations after suffering a shoulder injury playing for his club Ospreys in the European Rugby Champions Cup against Clermont Auvergne in January.
Biggar, 28, spent 90 minutes daily sitting in an oxygen chamber in a bid to speed up his recovery in order to be fit in time for the Ireland game.
"It's been a tough five weeks of rehab and working with the conditioners. I don't think I could have done anything more to make sure I was ready," he said.
Biggar returns to the side along with fellow Lions Leigh Halfpenny and Liam Williams as Wales start to welcome back many of their stalwarts from injury.
(Reporting by Mark Gleeson, editing by Toby Davis)
