Ford’s championship chasing Mark Winterbottom says his 150th V8 Supercars event this weekend could be decisive for his title hopes.

Sunday’s Sandown 500 marks the start of the three endurance races on the V8s calendar.

At the scene of his first event in 2003 and now his 150th, Winterbottom said the 300 points on offer for a race win will bring the series alive.

“You work out whether you’re a contender during these races,” he said.

“When you come out of enduros into the run home, you know what you have to do on the run home.”

The reigning Bathurst champion has arrived at Sandown without 2013 co-driver Steve Richards – now with Craig Lowndes – and will instead share a seat with Steve Owen.

Importantly for “Frosty” the change-up to longer racing also brings a chance to halt series leader Jamie Whincup’s championship momentum.

After seeing the Red Bull Racing champion erode and replace his lead in recent rounds, Winterbottom says he only has himself to blame.

“(Whincup) hasn’t been that good in the recent rounds, we’ve just been bad to be honest,” he said.

“In terms of race pace we’ve been competitive with him, but he’s qualified well and gone on and marched up the order.”

Unfortunately for Winterbottom, a gap in race pace emerged in Friday’s practice session.

Whincup and co-driver Paul Dumbrell impressed, with Whincup fastest of all.

The series leader’s 1:09.19 lap beat home Garth Tander and James Courtney ahead of Saturday’s qualifying.

Alexandre Premat, in Scott McLaughlin’s Volvo, was the quickest of all co-drivers ahead of Dumbrell by less than 0.04 seconds.

Car No.6, belonging to Winterbottom’s Ford Performance Racing team-mate Chaz Mostert, found the top of the timing charts early but then languished.

Co-driver Paul Morris – more than double Mostert’s age at 46 – was amongst the slowest in Friday’s second practice.

Mostert backed Winterbottom, who charted ninth in a handful of laps, to re-discover his winning ways at Sandown.

“Frosty needs to get his boots back again, the last couple of races has been a bit of a struggle, but he’s got a great partnership,” he said.

“A lot of things have got to go my way to get a podium – I’d be happy with a couple of top ten finishes to keep chasing top five in the championship.”