Lucas Herbert holds a one-shot lead over Jason Day at the halfway mark in the Australian Open as Jordan Spieth failed to make his presence felt in the second round on Friday.
Victorian youngster Herbert capitalised on good conditions at The Australian Golf Course to card a five-under 66, moving to the top of the leaderboard on nine under.
The 21-year-old made four of his six birdies on the front nine, dropping just the one shot at the last after being forced to lay-up.
Day is ominously poised after following up an opening 66 with a three-under 68, reeling off four birdies in a row on the back nine in a mixed round which included four bogeys.
The 2015 US PGA Championship winner was a joint-leader with Herbert after a sinking a long birdie putt at 15, but made a mess of an approach shot at the 17th to drop back to eight under.
Day said: "I haven't won this year. This would be a nice little end-of-year cap, knowing that it wasn't a disappointing year. A win is a win regardless of where you play. To have the Stonehaven Cup on the mantle would be great.
"I know I just don't want to win one of these; I want to win multiple Stonehaven Cups and Australian Opens."
Cameron Davis, the leader by two strokes after the first round, is two shots adrift of Herbert following a one-over 72.
Defending champion Spieth is back on one under after signing for a 71 and will have to produce something special this weekend to retain his title.