Jason Day has revealed that he was unaware of how close he is to scoring a 59 in the first round of the BMW Championship.
Yesterday's first round was postponed due to heavy rain at Conway Farms just after Day had fired his tee shot down the ninth, his 18th and last hole of the day.
Day is currently 10-under-par for his round and will go below 60 if he holes his second shot from 44 yards after smashing a 346-yard drive down the par-four ninth.
However, it was only when playing partner Jordan Spieth told him that the Illinois course was a par-71, not 72, that Day realised how close he was to a rare 59.
Speaking to reporters after the abandonment of Thursday's play, Day said: "I'm walking through the locker room now and guys are asking me if I'm playing the ladies' tees.
"Jordan told me on nine it was a par-71 and I had a chance at 59. I probably should have known that.
"It feels like a practice round. Like even if you hit a bad shot, it's going to be okay. It's hard to explain."
Daniel Berger is Day's nearest challenger on six-under, with Spieth a further shot back.