17-year-old golfer Ryan Ruffels declared himself as a professional earlier this week and will become the youngest Australian pro to ever play on the PGA Tour later this month. Ruffels was the 13th ranked amateur golfer in the world at the time of his decision, and in 2014 finished in 17th place in a field full of professionals at the Australian Masters, just a few shots behind Masters champ Adam Scott.

Phil Mickelson may have underestimated Ruffels in a practice round he played with the teenager, and it cost him $5,000. In an interview with the Sydney Morning Herald, Ruffels revealed that he made a bet with Mickelson and made a furious charge on the back nine to win.

Via the Sydney Morning Herald:

“We get on the first tee, it’s pretty early in the morning and he says, ‘I don’t wake up this early to play for any less than $2500’,” Ruffels recalled of a friendly offer made to him by Mickelson. The 42-time US PGA Tour winner gave Ruffels 2-1 odds; if Ruffels won, Mickelson would give him $5000, if he lost, Ruffels would have to pay up $2500 when he turned professional. “I was a few down through nine but then I birdied six of my last seven to win by one shot and took his money, so that was pretty cool.”

Ruffels hopes to play in at least seven PGA Tour events this season, and will be in the field at the Farmers Insurance Open at Torrey Pines on January 28th.