Jamie Whincup declared that topping practice in Sydney “means a lot” ahead of Saturday's penultimate qualifying session of the season.
Without a final Saturday morning practice session this weekend, the front-runners each used a new set of tyres in the dying stages of the Friday running.
Click here to have your say on the state of Australian motorsport and go into the draw to win a Kincrome Tool Armour Workshop valued at $11,999.
Whincup's team-mate and closest title rival, Craig Lowndes, was slightly further back in seventh.
“We certainly needed the hour and a half worth of running today,” said Whincup, referencing the fact that all four 30 minute hit-outs were run on Friday.
“We chipped away at the car to try and improve it and we did a reasonably good job.
“I didn't quite have the tyres up to temp at the start of the (quickest) lap but we came home strong.
“It certainly means a lot (to top practice) because we're all out there trying to go as fast as we can,” he added.
“It doesn't mean anything mentally, but it certainly does technically because it shows we've made a good start to the weekend.”
Winterbottom and Lowndes also admitted to having to work hard to dial their cars in while on older rubber during the earlier sessions.
“In the end it was quite good but we struggled a bit throughout the day,” said Winterbottom.
“You bring tyres and they have numbers written on them (previous mileage) that say they're meant to be ok, but the first set of tyres I had were pretty average; I almost had a big shunt on the outlap.
“When you put new tyres on it makes a big difference and you almost have to restart again.
“It feels ok. We're obviously up the front somewhere and we'll tune it up, hopefully qualify well, put some pressure on and just not hold back and have a go.”
Lowndes admitted that he “needs to find a little more” before qualifying, but was typically upbeat.
“The car is very different to what we had last year, so getting the car set up to ride the kerbs is a bit of a challenge,” he noted. “But all in all I'm quite happy.”
Whincup heads into the weekend's fight with a 20 point championship lead and a record equalling fifth title in his sights.
The Red Bull driver insists he's not worried about his poor previous record at Sydney Olympic Park, but is typically painting himself as the underdog.
“I've blocked it out,” he said of his Sydney scorecard, which does not include a single podium finish in eight starts.
“There's been no common trend why I haven't been on the podium here, it's been a little bit of everything.
“I remember we've had poor strategy, some pretty ordinary driving one year… a little bit of bad luck, but we've had good pace.
“I'm not too concerned, but I'm certainly aware that I'm possibly, I wouldn't say a long shot, but Lowndesy has been the most successful driver around this place so he's going to be incredibly hard to beat.
“I'm going to have to do something a little bit unexpected to beat him this weekend.”