Williams boss stresses he still has faith in benched Logan Sargeant

With Williams only bringing one chassis to Melbourne, Albon will race in Sargeant's car after wrecking his own in Friday's first practice at Albert Park.

Sargeant scored one point in his rookie season last year with Albon scoring 27, which lifted Williams to seventh overall in the constructors' championship.

Vowles told reporters on Saturday that Sargeant was disappointed but had taken the blow with maturity.

"He took it with far more maturity than I would have done at his age and, in fact, more so than that, his response after a considered moment was one more of, ‘How do I help, how do I move forward with the team?', fundamentally," Vowles said.

"You will always question yourself in all of these (situations). But all I did is lay out the facts to him (that) he has improved, he is closer to Alex than before, but he’s not quite at the leading edge and in front of Alex," Vowles added.

Motor racing pundits said the driver swap-out underlined a lack of faith in Sargeant but Vowles said he still backed the American to improve.

"In the case of Logan, I haven’t changed my mind. I’ve signed him and I’ve put my full weight behind him because I believe in him," he said. "If you look at his results this year, he’s been within milliseconds of Alex. The gap (between them) has closed down as I expected it to, but in the circumstance he’s not quite on the leading edge."

Williams is one of four F1 teams that has yet to score a point ahead of Sunday's race.