It is curtain-up on Sunday after the three-week interval on a thriller of a Formula One show set to run and run.

And it could spell the return to star quality of faded leading man Sebastian Vettel, whose enigmatic stumble down the rankings from world domination is a puzzle baffling the entire grand prix scene.

Few, if any careers, in F1 have undergone such a vivid turnaround and the 27-year-old four-time champion has used the break to reflect on his reprisal plans at his remote village home in Switzerland.

Mastery has turned to misery and his Red Bull boss Christian Horner, far from being critical, has in his wisdom striven to sustain Vettel’s confidence which, in the face of his teammate Daniel Riocciardo’s two-win haul, has taken a bashing.

The reasons, variously offered, are intriguing. Has his status as a new father to a baby girl with his long-time girlfriend Hannah Prater re-directed his concentration? Is he tired? Has he spent all his energy in four years of unbroken, almost unchallenged, domination?

And, above all, can he come back from the shadows into the spotlight of Bernie Ecclestone’s spectacular show with so many fiercely ambitious upcomers, headed by Ricciardo, anxious to rob him of the opportunity?

Ecclestone, a firm friend who regularly plays backgammon with the German, and who often airlifts him in his private jet to and from far-flung circuits, believes a breakthrough is possible — but with a fresh team, possibly Ferrari.

And he told me: “With the right car, Sebastian won everything for four years. He was amazing. And when he has the right car again, he will win more world titles.

The simple reason is: “He is faster than everyone else. If Ferrari can make a fast car again, and they are working hard at it, that would be the place for him to go. He needs to be where the best car is.”

Ecclestone’s remarks will serve to underpin the rumours that the Italian giants have already taken tentative steps to sign Vettel on the completion of his Red Bull contract.

Meanwhile, Vettel will be dreaming of taking up where he left off at Spa last year with a commanding victory in fine style at one of his favourite circuits.

He admits: “Becoming a father has changed my priorities. I have somebody else to think about now.

“But I still try to manage the challenge of racing and want to do it better than anybody else.”

He blames the new regulations and changes to the cars for his mystifyng demise, and adds: “If you look at the raw performance, power and lap times, we are not going quick enough.”

The mystery is, if Ricciardo can do it why can’t he?

Horner, who has spent hours reassuring Vettel, believes he can — and will come back with a bang.

And, ahead of Sunday’s Belgium Grand Prix at super-fast Spa, he says: “The way Sebastian brought out those extra few tenths from his car when he was winning his titles was quite unique.

“But when you have fought so hard for the championships for five years, it does wear you out.”

If he is to halt the Mercedes title takeover, he will have to resurrect the genius that had him hailed as one of the greatest grand prix drivers of all time.

Starting this Sunday.