Speaking here on Wednesday, Hussey called on the Australian selectors to stick by the struggling Martyn, who averages 46 at the top level but is under mounting pressure to retain his berth for the Test, in which the home side will be looking to reclaim the Ashes.
The game will be played on Martyn's home ground, the WACA, starting on Dec 14.
But modest scores of 29, 11 and 5 in the first two Tests have the 35-year-old under the gun despite Australia's 2-0 lead in the five Test series.
Martyn's cause is helped by the fact that young Queensland all-rounder Shane Watson is still suffering from a hamstring problem and looks unlikely to be available for the third Test.
Hussey said suggestions Martyn's Test career was over were premature.
"I think that is grossly unfair," he said. "He has been in outstanding form and cricket is such a great leveller, it just takes one good ball and you are out.
"I am sure the selectors will show faith in Damien...he is a vital member of our team. I certainly hope he is still in our team."
Martyn was one of the stars of Australia's historic Champions Trophy win earlier this year, but has just one hundred and two half-centuries in his last 21 innings in Test cricket.
His most significant rival for a berth in the Australian top six is Watson, but he was missing from the Queensland side that played New South Wales in a one-day game on Wednesday.
Watson is also expected to miss Friday's one-day clash with South Australia, a major blow to his chances of a Test recall.
Hussey denied there was anything sinister in Martyn's demotion to fifth in the batting order on the final day of the Adelaide Test and said it was a simple ploy to combat English spinner Ashley Giles.
"We wanted to keep a left hand-right hand combination all the way through," he said.
"If Matty Hayden got out, I was going to go in and if Ricky (Ponting) got out Damien was going to go in and that was going to continue down the batting order."
The English are in dire trouble after the Adelaide loss, with inspirational captain Andrew Flintoff clearly battling ankle soreness, their attack lacking venom and their team selection for the second Test coming under fire.
However, Hussey dismissed suggestions the English would be a broken side after their incredible defeat in Adelaide.
"They are a pretty resilient bunch," Hussey said.
"I'm sure they will really bounce back in the Perth Test and put up another good show. "I don't think we have broken them or anything like that," he added.