Ferrari's challenge to Mercedes was a shot of adrenalin to Formula One's heart, providing the edge that had been missing since the turbo-hybrid formula was inaugurated in 2014 as the advantage flowed between Lewis Hamilton and Sebastian Vettel. Here are my five highlights of the season:

RACE 1, AUSTRALIA: VETTEL'S WIN SETS TONE FOR SEASON

Vettel proved conclusively that Ferrari's testing form was real, when he scored a crushing 9.9-second win over the Mercedes of Hamilton and Valtteri Bottas in Melbourne's season-opener.

It was like a boxing match in which the favourite got knocked off his feet in the first round.

Vettel owned the race andfrom the moment he went ahead, he never looked like losing.

The previous year, Ferrari lost this race through poor strategy; this time there was no way they were going to let a crucial psychological victory slip away, and it signalled just how intense their challenge would be.

RACE 7, CANADA: HAMILTON FINDS HIS SIXTH SENSE IN MONTREAL

Hamilton went to his happy hunting ground of Montreal licking his wounds and wondering just where his Mercedes' famed poise had gone around the streets of Monaco, where he had struggled home a poor seventh.

With his Silver Arrow ponderous and Vettel's Prancing Horse nimble and fast, he desperately needed to strike back, fast.

He dominated to take his sixth Canadian GP victory but Vettel, by fighting back to fourth following a first-lap clash with Max Verstappen, did his own damage limitation and left Montreal still 12 points ahead.

But the battle between F1's two heavy hitters was re-engaged.

RACE 8, AZERBAIJAN: RICCIARDO TRIUMPHS, HAS THE LAST LAUGH

This one had it all. A hugely popular opportunist's victory for Daniel Ricciardo and Red Bull; acrimony well and truly out in the open between Hamilton and Vettel after the German had collided deliberately with his arch-rival while running under the safety car; a silly glitch with his car's headrest which cost Hamilton victory; a brilliant climb back from early adversity by his team-mate Valtteri Bottas; and a rookie - Lance Stroll - running second to within sight of the flag and finishing on the podium in his first season.

It was the first manifestation of weakness from one of the two leading protagonists, as Vettel lost his cool and was hugely lucky not to be penalised more heavily for an act which raised questions about just how much the pressure was getting to him.

As Hamilton quietly suggested that the German had disgraced himself, a speechless Ricciardo admitted that he was giggling like a schoolboy on his slow-down lap. Hamilton and Vettel most definitely weren't.

RACE 12, BELGIUM: HAMILTON'S SUBTERFUGE PAYS DIVIDENDS

Hamilton's innate racer's cunning would play a major role in cementing a crucial triumph at the majestic Spa-Francorchamps, with Ferrari able to match their rivals for speed in a tense race.

It seemed inevitable that the German would sail past the Englishman after stalking him mercilessly, but when his one main chance came on the 34th lap after a safety car period, Hamilton backed Vettel up at precisely the right moment. Vettel, in his faster Ferrari, got very, very close to the back of the Mercedes on the run down to Eau Rouge but as Hamilton feathered his throttle, Vettel got a mite too close, too soon, and had to lift momentarily.

Hamilton ensured thus that he could not be slipstreamed out of the lead as they climbed the Kemmel hill to Les Combes at the top of the circuit.

RACE 18, MEXICO: VERSTAPPEN IN SMASHING FORM IN DECIDER

Who will ever forget the sight of Vettel, Verstappen and Hamilton heading into the first corner three abreast? Or the clash that saw the young Dutchman dispatch Vettel, who lost control and damaged his nose as he split Hamilton's right rear tyre?

Mexico was hyped up for a World Championship decider and it got one, as Vettel and Hamilton staged brilliant comeback drives, the latter to cement his fourth title with what he said was a disappointing ninth place.

And the man widely regarded as the sport's future yet again insouciantly put it across his more experienced rivals to underline his precocious talent yet again.