Before last night, United had never overturned a two-goal deficit in the Champions League knockout stages, although 30 years ago they did it in the Cup Winners’ Cup against Barcelona.
Bryan Robson was the hero back in 1984 as he outclassed Diego Maradona et al to help the Red Devils come back from 2-0 down to knock out the Catalan giants.
And with their season here on the brink of descending into mediocrity United found, in van Persie, a player of Robson’s ilk, though not necessarily identikit in personality, to virtually drag them into the quarter-finals of the European Cup single-handedly.
In truth, van Persie has been below his best this season, and there had been talk of him being unhappy with life at Old Trafford.
But there was little evidence of that last night as he breathed new life into a campaign hitherto characterised by frustration with a brilliant and inspired hat-trick that could prove to be a huge moment for Moyes.
The only sour point for the Dutch striker was leaving the pitch on a stretcher late on after clutching the back of his leg, although Moyes said later: “I don’t think he’s too bad. He’s got a knock just behind his knee. We’ll know more in the morning.”
While his strike partner received attention to that knock, Rooney took time out to praise the supporters who had suffered so badly during sunday’s capitulation to arch-rivals Liverpool.
“The fans in particular against Liverpool were fantastic and again tonight were brilliant and they deserved this,” said Rooney. “It’s a big result and performance and we’re delighted.”
Veteran Ryan Giggs defied his 40 years to control the game from midfield and echoed Rooney’s thoughts.
“We owed the fans this result,” he said. “It was always going to be tough not to concede a goal.”
Van Persie certainly galvanised his team-mates in a way that this team have been crying out for lately.
United had only lost once against Greek opposition — in the first leg of this last-16 tie — and there was a fierce determination among the players and manager as if victory here would erase that from the history books forever.
United set out at a blistering tempo in the early stages and Rooney brought an unorthodox save out of Olympiacos goalkeeper Roberto from a swerving free-kick.
The livewire Rooney appeared on the right flank shortly afterwards and whipped a ball into the penalty area intended for van Persie only for Ivan Marcano to block his route and Roberto was able to gather. It was an early warning of what was to come.
The United supporters held their collective breath in the 15th minute as Olympiacos — confirmed as Greek champions last weekend — carved open the United defence.
Joel Campbell left Phil Jones for dust with a stepover and cut the ball back from the byline for Hernan Perez who, with the goal at his mercy, fluffed his big chance and sent the ball high into the stands.
Rooney struck the post shortly afterwards with a header but United’s big opportunity arrived midway through the half when van Persie went down in the area after a barge from Jose Holebas and referee Bjorn Kuipers, pernickety and card happy in the early stages, pointed to the spot.
The Dutchman dusted himself off and made no mistake with the spot-kick and emphatically blasted into the corner of the net past Roberto.
“Attack, attack,” came the rallying cry from the Stretford End, however United’s positive intent left them exposed on the break.
On one such occasion they were fortunate not to be punished by Olympiacos when David de Gea made a brilliant double save to deny David Fuster’s header and Alejandro Dominguez’s follow-up from close range.
A monumental moment, and one that United were able to take full advantage of on the stroke of half-time when Giggs’s early pass found Rooney who squared for van Persie to finish clinically past Roberto from close range.
Old Trafford was allowed 15 minutes to recover from a breathless first period before van Persie added the third of his magnificent treble.
A scurrying run by Danny Welbeck saw United awarded a free-kick in a dangerous position. The position seemed to suit Rooney, but he dummied and the left boot of van Persie curled the ball home past a static Roberto.
Olympiacos still gave the hosts a few hairy moments.
United were given a let-off when David Fuster could only direct his shot from Campbell’s cross straight at De Gea just after the hour.
The Greeks continued to press and Old Trafford certainly grew more nervous with five minutes of injury-time added on. Fortunately for the Red Devils and Moyes that away goal never came.
For Moyes the result was badly needed after the shock of Sunday’s defeat to Liverpool.
He said: “I don’t want to say this is the moment [turning point] but in the same breath I really hope it is. I genuinely think this club is capable of it [winning the Champions League]. If we play to our capabilities, which we have not done enough.”