Only eight players ended the round in red figures as blustery winds and baking greens turned so-called moving day into grinding day at The Australian Golf Club.
And Scott was predicting more of the same today as 23 players within six strokes of the lead battle it.
"In these conditions, it's going to take an incredible round just to make sure you're in with a chance the last few holes," he said. "You probably saw it slipped pretty quickly for a few guys out there today and, if you're not careful, that can happen and I certainly don't want to do that.
"So it will be a thinking hat on right from the first tee."
Of the frontrunners, Scott will carry the momentum after rebounding from a horror five-over start on the front nine on Thursday.
"I wasn't feeling great going to the 10th tee and managed to claw my way back and hopefully I'll have a shout when it comes down the last tomorrow," said the world No3.
Long-hitting amateur Todd Sinnott (73) is outright sixth at two under - two behind Scott and one ahead of rising star Jake Higginbottom (72) and Sydney touring professional Aron Price (69).
Queenslander Daniel Nisbet fired the round of the day in the easier morning - a bogey-free four-under 67 - to surge up the leaderboard into equal ninth at even with the card.
Chalmers rebounded from a bogey-bogey start with birdies on the sixth and 14th holes to retain a share of the lead in his bid to join some of golf's all-time greats, including Jack Nicklaus and Gary Player, to win at least three Australian Open crowns.
Spieth, the world No14 and 2014 Masters runner-up to Bubba Watson, showed his class to birdie the last to join Chalmers and Rumford on top.
Rumford mixed four birdies with two bogeys for a shot at winning a maiden national championship.
Pampling, 45, ignited his round with a spectacular eagle two on the 401m par-4 10th. Holing out from 120m, Pampling rode the momentum all the way through the back nine.
