Ford's Scott McLaughlin defied treacherous conditions to top the opening practice session of the Supercars meet at Winton.
McLaughlin's lap of one minute and 43.3667 seconds was the fastest in Friday's first practice at the sodden track in Victoria's north-east.
Nissan's Kelly brothers negotiated the slippery conditions well, with Todd second fastest, 0.31 of a second behind McLaughlin, and Rick fourth in 1:43.7439.
Holden star Jamie Whincup was wedged in between the Kellys, while McLaughlin's DJR Team Penske teammate and championship leader Fabian Coulthard rounded out the top five.
Heavy rain got worse as the session wore on, with most drivers finishing early as large puddles formed on the track.
A slew of drivers came off the track including Taz Douglas, who got bogged and caused the sole red flag of the session with a little more than 13 minutes remaining.
Nick Percat and Scott Pye's cars made contact at the second turn, with the latter's Holden suffering rear damage.
Chaz Mostert's Ford also suffered rear damage after contact which he believed was caused by Coulthard.
Showers are expected to ease in time for Saturday's opening race, while Sunday is expected to be mostly fine.