Sydney - Jason Day reeled off four birdies in a row to charge up the leaderboard at the Australian Open on Friday, after world number two Jordan Spieth birdied his final hole for the second day in a row.
Playing in the afternoon when the wind was strongest, Day defied blustery conditions to shoot a second round three-under par 68, to reach the halfway point at eight-under.
That left the Australian just one stroke behind outright leader Lucas Herbert, who made the most of his early tee-off time and carded a 66.
Spieth, still rusty after taking an extended break since the Presidents Cup, battled his way to an even-par 71 to be one-under overall but was still hopeful of catching up to the frontrunners over the weekend.
"On this golf course, more than just about any that we play, I feel like you can make up more ground and come from behind," he said.
Day, chasing his first victory of 2017 and his maiden win at his national open, briefly joined Herbert in a share of the lead when he drained a 20-foot putt on the 15th hole for his fourth successive birdie.
The former world number one slipped a shot behind when he bogeyed the 17th but then scrambled to make par on the last after finding a bunker with his drive.
Herbert followed up his first day 67 with six birdies to set the pace with a nine-under 133 and remain in front.
The recently-turned professional also led the Australian Open last year before eventually finishing 20th, but said he was better equipped to handle the pressure this time.
"I finished pretty high up last year in the Aussie Open (so) I can play well and I'm proving to myself that I can play well in these big events against these big players," Herbert said.
"I'm feeling like I belong out there, which is the big thing."
Hoping to capitalise on the benign morning conditions after playing his opening round in gusting winds on Thursday, Spieth only managed two birdies in the second round.
The world number two has not played in six weeks and is missing his regular caddie Michael Greller, who remained at home after the recent birth of his son.
But Spieth said he was making progress.
"It's just been the short game rust that's kind of hurt me a bit the last couple of days that prevents me from being five or so under and then instead I'm at one," the American said.
"But the more I'm getting them on course the better, and we'll go forward and try and shoot a low round."
Leading scores after the second round of the 102nd Australian Open
golf championship at the par-71 Australian Golf Club on Friday:
133 - Lucas Herbert (AUS) 67-66
134 - Jason Day (AUS) 66-68
135 - Cameron Davis (AUS) 63-72
136 - Anthony Quayle (AUS) 67-69
138 - Cameron Smith (AUS) 69-69, Matt Jones (AUS) 71-67, Nick Cullen (AUS) 66-72, Richard Green (AUS) 70-68
- Dale Brandt-Richards (AUS) 73-66, Jack Munro (AUS) 71-68, Jason
Scrivener (AUS) 69-70, Taylor Macdonald (AUS) 65-74, Ben Campbell (NZL)
140 - Rhein Gibson (AUS) 72-68, Craig Parry (AUS) 73-67,
Jonas Blixt (SWE) 68-72, Travis Smyth (AUS) 71-69, Matthew Guyatt (AUS)
141 - Jordan Spieth (USA) 70-71
142 - Geoff Ogilvy (AUS) 69-73
146 - Mike Weir (CAN) 77-69