A late effort from David Reynolds denied Nissan’s Todd Kelly the fastest time in opening practice at the Watpac Townsville 400.
Kelly had been the first into the 1:12s bracket after 18 of the 40 minutes with a 1:12.99s aboard his Carsales Altima.
The time stood as the fastest until Reynolds moved to a second set of tyres on his Erebus Holden and went 0.1s quicker with one minute remaining.
"It’s been really good since we rolled it out," said Reynolds.
"We only did a couple of runs then. I’m not 100 confident with it.
"My mid-sectors through the fast stuff… it’s all over the place.
"The way we run our cars now it tends to be worse for that around 5 and 6, those fast left and rights in the middle of the track."
Kelly, who didn’t do a late run on a second set, said he was pleasantly surprised by his time.
"We’re just trying to work out what we did then and how we’re going to do it again, basically. I was quite surprised," he said.
"The lap felt 8/10 and it was fastest for most of the session. I think a few people put another set of tyres and even greens on.
"We’ve got a bit of stuff to look at but hopefully we can stay up that end."
Triple Eight team-mates Shane van Gisbergen and Craig Lowndes were third and fourth respectively.
The latter endured a high-speed spin at the exit of Turn 6 with 10 minutes remaining before jumping from 17th to fourth with a late run on a second tyre set.
"We actually tried some things we normally don’t try and it didn’t work. Everyone can see that," said Lowndes.
"It reacted differently to what I was expecting and it did catch me out going through that fast chicane.
"We’ve still got a bit of work to do. The car’s not perfect, but it’s good enough to do a time like that."
Tim Slade, Chaz Mostert and Garth Tander filled fifth through seventh, with the GRM Holden driver fastest to the second sector late in the going before a mistake at Turn 11.
The championship’s top three had quiet sessions, with Fabian Coulthard improving late to be ninth, team-mate Scott McLaughlin 13th and Jamie Whincup 12th.
McLaughlin was fastest in the early minutes but failed to improve thereafter – aborting a lap mid-session when he caught Simona De Silvestro.
The entire field was covered by just 1.6s, with Lucas Dumbrell Motorsport’s late call-up Aaren Russell less than 0.2s adrift of team-mate Alex Rullo at the bottom of the order.
The day’s second 40 minute session will get underway at 1505 local time.