After losing to Australia by 218 runs in Adelaide to slip 2-0 behind in the five-match series, a performance Prior labelled "embarrassing", England's chances of retaining the Ashes are fading fast. (Agencies)
With team manager Andy Flower calling for the squad's senior players to stand up, Prior said this week's third test in Perth will be the ultimate test of their resolve.
"How tough are we?" Prior said in his column in the Daily Telegraph on Tuesday. "We always ask those questions in the dressing room and in meetings.
"Now we have to prove it in the real world. We cannot run away from what is ahead of us.
"We know what we are up against. We like doing it the hard way and it does not come any harder for an English cricketer than having to go to Perth and win. But if we manage to come back it will be one of the best fightbacks ever."
Prior said some of the flak flying England's way has been hurtful, but admitted it was justified.
"People are questioning our desire and hunger and that really hurts because it means we have been giving the wrong impression but nobody wants to win the Ashes more than us," he said.
"The first innings collapse at Adelaide was as embarrassing a performance I've been involved in with England.
"We were horrendous and there have been honest chats and words spoken. Everyone in this dressing room has been in a dark place and knows the feeling of walking out to bat thinking: 'I don't know what is going on'.
"But you have to work hard and have faith it will change around."
Prior's fighting 69 and Kevin Pietersen's 53 in the second innings at Adelaide were the kind of performances Flower wants more of from his senior players.
"In these sorts of contests and series where the intensity levels are high, you do need your more experienced players, players who have been through similar situations in the past, to come through tough periods and play match-defining innings or produce pressure to create chances with the ball," Flower told reporters in Adelaide.
Joe Root, who will turn 23 at the end of this month, currently averages the highest among batsmen while senior bowlers James Anderson and Graeme Swann have been largely off-colour in the first two tests.
"We've been outplayed in these two tests, very obviously, and the Australians have outplayed us in all three facets," Flower said of the crushing defeats in Brisbane and Adelaide.
"We haven't been skilful enough for long enough to get into better positions in the matches. That's the crux there."
England need a quick response in Perth where Australian paceman Mitchell Johnson will again be the dangerman, having ripped England's batting apart so far.
"I wouldn't say scared," Flower told reporters when asked about the effect that Johnson has had on the batsmen's minds.
"He's bowled at good pace but that's what you expect in test cricket. One thing I would say about playing fast bowling is that our batsmen have to display the combination of skill and determination to bat long periods against it."
Spinner Swann said Johnson had been the main difference between the sides so far.
"He has struck a purple patch and is bowling very fast," Swann told The Sun. "He might not be the most skilful bowler with what he does with the ball but he has that raw pace and is causing us problems."
After losing to Australia by 218 runs in Adelaide to slip 2-0 behind in the five-match series, a performance Prior labelled "embarrassing", England's chances of retaining the Ashes are fading fast.