Red Bull Racing principal Roland Dane says New Zealand driver Shane Van Gisbergen's hopes of retaining his Supercars title are over.
Dane is blaming balming the engineering team saying they threw away success int he Sandown 500 with an aggressive car setup.
The race was won by pole-sitters Cam Waters and another New Zealand driver - Richie Stanaway.
Van Gisbergen began in 21st and surged to sit third until a tyre blowout with less than 20 laps left.
He finished 13th.
Dane says the blowouts weren't random, but his team's own fault.
"It was not bad luck. It's not doing a good enough job. We were too aggressive," he said.
"We lost points when we should have won that race fairly comfortably.
"The engineering group takes responsibility for it, exactly as they should.
"The cars were fast and we didn't need to do anything else. We had the race in the bag."
The result grows the buffer between Whincup and series leader Scott McLaughlin from 12 points to 84.
Reigning champion Van Gisbergen dropped from fourth place in the standings, and 258 points behind McLaughlin, to fifth and 420 points adrift.
Dane conceded it was the likely end of his title hopes.
"We'll see what Bathurst brings but I suspect Shane and Fabian (Coulthard) are not in (the title race)," he said.
"There are two people who really are in it. We'll see what happens over the course of the last four events but I think there are two people in the championship (battle)."