Ilonen travelled 15 hours from Helsinki to San Francisco as the tournament's first reserve, but has now been paired with reigning Masters champion Jordan Spieth on the first day of the tournament.
While many people have already written Ilonen off, the 35-year-old believes that it would be a grave mistake to do so.
"Hey, it’s match play and anything can happen – we all know that," Ilonen told reporters. "I definitely don’t have anything to lose against Jordan. If you look at how good he has been recently, and as much as I hate to say it, how bad I have been lately, then there really is nothing for me to lose."
Despite his poor form as of late, Ilonen believes that his fortunes could change for the better when he steps out onto the course at TPC Harding Park.
"My form has been poor but we know how quickly it can turn in this game and maybe match play is what I need to get to going," he said. "I have a pretty good match play record and I have to say that wining the Volvo Match Play at the London Club last year was basically got me into this tournament.
"That win is basically what got my ranking high enough to sneak in here and beating a lot of the European Ryder Cup players in that tournament so soon after they had won in Gleneagles gave me a lot of confidence and belief that I can do well in this format.
"No matter what happens this week, I am here to enjoy and see what happens."