"I walked off the front nine pretty p***ed off to be honest and then I holed an eight-footer for birdie on 12 and it relaxed me a little bit.
"It's the first time I've had fun on a golf course for a while and you don't expect to do that but it was nice to just enjoy being part of such a great event.
"I don't think I quite got in the zone - I know that sounds strange but I've only been in it once or twice before when it gets to a point where you just see it and hit it.
"But it certainly wasn't like that. I don't think this golf course lets you do that because you have to think about so many humps and hollows."
He bogeyed three of his first nine, so lies three-under for the tournament in a share of fifth, one shot off the lead.
Listen to "Radio Sport Breakfast talk to Ryan Fox" on Spreaker.
Fox turned professional in 2012 and is now an integral part of the Open record books.
The big hitter from New Zealand is playing in just his fourth Open, with his best finish to date coming last year when he finished T39.
Royal Portrush has already proven to be a very challenging golf course for this year's Open, with Rory McIlroy, the home favourite, shooting an eight-over 79.
At the other end of the spectrum, David Duval hit the highest score on a hole in Open history, with former Open Champion scoring a 13 on the par-5 7th.
Fox finished the front nine three over par, not a disastrous score by any means but certainly room for improvement. Well improve he did and by some margin.
After parring the 10th and 11th, Fox then birdied four holes in a row, before parring the dreaded 220-yard par-3 16th known as 'Calamity' and then finishing with two more birdies on 17 and 18.
There's a four way tie at the top, with Irishman Shane Lowry holding the clubhouse lead alongside four-time major winner Brooks Koepka [kep-kuh], Englishman Tyrell Hatton and Spaniard Jon Rahm.
Northern Irish local Rory McIlroy has had a round to forget, quadruple-bogeying teh first and shooting eight over to lie 150th.
