By Paresh Soni
BBC Sport in Perth
After England went 2-0 down to Australia at Adelaide, the cry from their supporters, and commentators on both sides was: "Where is Monty?"
Panesar is the first Englishman to take a five-wicket haul in Perth
Very early on day one here, the cry from former Australia paceman Geoff Lawson on Test Match Special was similar.
"Where have they been keeping this guy Monty?" he said. "Seriously, where the hell have they been keeping him?"
It was a good question.
Despite an encouraging start to his Test career, which saw him claim 32 wickets in 10 games, Panesar was overlooked for the first two Ashes Tests.
The more experienced Ashley Giles was believed to offer more with the bat and in the field.
But, belatedly, the selectors recognised the most important currency for bowlers is wickets.
And on a hot day in Western Australia, after the hosts had won the toss, young pretender Panesar showed he was a handy trader in it.
His performance was far from perfect, despite finding a way through veteran opener Justin Langer's defences early on.
As he tired in the afternoon he dropped the ball shorter, with Michael Clarke and Michael Hussey punishing frequent errors.
The big-shouldered Andrew Symonds also went after him, smashing 14 in three deliveries.
The home fans - who had pounced on every slight error in the field - were lapping up his misfortune and dismissing his threat.
But not for the first time in his career, the 24-year-old showed real strength of character.
It was the same mental fortitude which has helped him deal with light-hearted, even affectionate, ribbing of his fielding and batting abilities.
There is no shortage of skill either - anyone who can count Sachin Tendulkar, Rahul Dravid, Inzamam-ul-Haq and Mohammad Yousuf among his victims has to be blessed in some way.
And following a brave piece of captaincy from Andrew Flintoff, Panesar had his revenge over Symonds before deceiving Adam Gilchrist.
Shane Warne perished after tea and Brett Lee was lbw to a beautiful delivery to make it five wickets and five vigorous celebrations.
Not bad for your Ashes debut.
The knowledgeable home members, previously suspicious of the patka-sporting cult hero, were suddenly forced to sit up and recognise what the fuss had been about.
Indeed, having competed and more than held his own against subcontinental spin experts India, Sri Lanka and Pakistan, Panesar had now demonstrated his ability to mix it with the best side in the world.
Giles, meanwhile, was seen smiling on the balcony, genuinely delighted at Panesar's success.
With all due respect to the King of Spain, it is a role he might have to get used to playing.