Starting Friday with the lead at The Lakes, An watched as American Matt Kuchar and Australian amateur David Micheluzzi entered the clubhouse at seven under par after playing in the morning wave.

But An shot back to the top of the leaderboard with an ace at the 197m par-3 15th that rocketed the former US Amateur champion to eight under.

"Hit it good, nice fading back to the hole and went in. This is my third one but first with a prize," the smiling Korean said after earning himself a $17,000 Swiss watch.

"It was a soft seven iron. I didn't even know the distance. My caddie just said to hit seven iron and take five (metres) off."

Earlier, world No.29 Kuchar lived up to his billing as the highest-ranked player in the field by taking the clubhouse lead.

Kuchar fired a five-under 67 and was joined atop the leaderboard shortly after by Micheluzzi (69) and last week's NSW Open winner, Jake McLeod (67), in the afternoon.

An had the final say, though, ensuring he would enter the weekend in front following his spectacular late heroics.

Fellow tournament drawcard and world No.30 Keegan Bradley returned an impressive 66 to sit a shot back at six under, sharing fifth with a bunch of players including Jordan Zunic (65), Cameron Percy (69), Marcus Fraser (69), Matt Jager (70) and Mexican Abraham Ancer (69).

Micheluzzi is bidding to become the first amateur to win the Stonehaven Cup since Aaron Baddeley in 1999 and jumped out of the gates on Friday with three birdies and an eagle in his first six holes.

Although the 22-year-old suffered three consecutive bogeys around the turn, he responded with a birdie at the third (his 12th).

Cameron Davis's eventful defence of the Stonehaven Cup, meanwhile, has continued.

After opening his first round with a quadruple eight on the way to a four-over 76, Davis dunked two more balls in the water on the par-5 11th to rack up a disastrous triple bogey on his second hole on Friday morning.

But the 23-year-old bounced back superbly with successive birdies then an eagle on the par-5 14th.

Davis then went two under on his closing nine to card an impressive 69, which brings his open total back to one over and he sits inside the projected cut line.

Australian Associated Press