David Reynolds has thrown down the gauntlet to V8 Supercars series leader Mark Winterbottom in Phillip Island practice.

In the only dry practice session of the meet, Reynolds was quickest around the coastal circuit.

Reynolds is Winterbottom’s closest rival for the championship, which resumes on Saturday afternoon.

Drivers will compete for 150 points across two 60km sprint races which begin at 3:10pm and 4:55pm (AEDT).

Winterbottom’s lead currently sits at 239 points from Reynolds, with Craig Lowndes a further point back.

The series leader was fourth fastest, with Lowndes 10th.

The most lively activity of the morning on Phillip Island took place in the Lucas Dumbrell Motorsport garage.

A late-developing illness to Nick Percat required a dramatic driver change.

Team principal Lucas Dumbrell threw a last minute invite to his older brother Paul Dumbrell – Jamie Whincup’s endurance season co-driver – which he accepted.

After a mercy dash from Melbourne, Paul ran into the garage wearing a Red Bull Racing jacket.

With just minutes before Saturday’s practice session, he swapped his jeans for a spare Lucas Dumbrell Motorsport driving suit.

The switch came so late in the piece that Dumbrell forgot to complete his paperwork – earning a black flag and to pit to sign the forms.

Percat has already left Phillip Island for Knox Hospital for treatment to his infected right foot, with Dumbrell to compete in all three races.