Mark Winterbottom has admitted he was surprised to end Friday’s practice fourth fastest in the Bottle-O Falcon at the WD-40 Phillip Island 500.

Celebrating his 200th round in the Virgin Australia Supercars Championship this weekend, Winterbottom was just 16th fastest in the opening 40-minute practice session.

He improved by over a second in the second session to end the day fourth overall, his 1:30.5409s just over half a second slower than pace-setter Jamie Whincup.

“To be fourth, I’m kind of surprised given the way the car felt,” Winterbottom said.

“I can feel where we’re weak, but it gives us something to work with to make it better.”

All four Tickford Racing entries had a tough weekend at Symmons Plains two weeks ago, leaving Chaz Mostert to suggest there was something broken in his car.

Though only practice, his Friday form at the Island is an encouraging sign for Winterbottom.

“We had a really bad last round, but we’re not a team that gives up. We get back up and have a crack,” he said.

“Two weeks is a short time, but they’ve done a lot of work. I’m happy with the result from (Friday), I can feel where the car is weak, but we need to make sure we don’t chase too much, but all in all a good day.”

Like Winterbottom, Mostert also improved by more than a second from Practice 1 to 2 on Friday, but the Supercheap Auto driver is still chasing more from his Falcon.

“We just stuck to our plan and tried really hard in the second session to make the car better, so if anything we learned the direction we’ve got to go to make the car quicker,” said Mostert after setting the 7th best time in Practice 2.

“It’s good to be in the ten, but I felt like we’re still a bit far away from what we need.”

Qualifying for the Phillip Island 500 begins at 1205.