It’s all about taking one race at a time, according to Nico Rosberg. It’s a simple strategy that so far in 2016 seems to have served him very well. It’s the next race, not the championship, he says, that he is thinking about.

But were he to pause and consider the state of play in the championship right now, and do the maths, Rosberg would realise that he could leave Mexico this Sunday night as the 2016 World Drivers’ Champion.

To do so, Rosberg must win the Mexican Grand Prix, while Mercedes-Benz team-mate Lewis Hamilton either fails to finish or finishes no higher than 10th.

Were the latter scenario to occur, Rosberg would be 50 points clear. Even if the German then went on to score no points in the remaining two rounds, and Lewis won them both, Rosberg would still be world champion on a countback of most race wins.

How things have turned in 12 months.

This time last year, Rosberg was a beaten man, humiliated by a gleefully rampant Hamilton. Lewis had clinched his third world championship title in Texas, with three rounds still to run. As they headed to Mexico, Hamilton had won a total of 10 races. Rosberg had won three. In the all-important battle for pole position, Hamilton had got the better of Rosberg 11 to four. And when Rosberg did get pole, more often than not Hamilton managed to beat him to the first corner.

But in Mexico, things suddenly changed. Whether it was a case of Lewis switching into off-season party mode with the title already secured, or whether it was a technical development on the car that favoured Nico’s style, a dramatic shift occurred. Rosberg was supreme, winning the remaining three races in a style as impressive as the most emphatic of Hamilton’s 10 earlier victories.

It was an odd way to end the season. Lewis went into the off-season break with celebrations of that cherished third world title (a big deal for Lewis personally in that it brought him equal to the tally of his hero, Ayrton Senna) annoyingly tempered after being shown up so comprehensively in the last three races by his hithero-conquered opponent; Nico was left to ponder what might have been if only he’d been able to do in the first 16 races what he did in the final three.

Nico Rosberg has defied his critics this year with a performance that could see him become world champion

Into the new season and Rosberg’s late-2015 burst of form re-emerged into a something more substantial as he claimed the first four wins in a row. Then in Spain came that celebrated opening corner clash between the pair that took them both out.

So it was that it took until the fifth race for the reigning champ to score his first win of 2016, at Monaco. And even then it came gift-wrapped, courtesy of a Keystone Cops-style pitstop debacle from the Red Bull team for Daniel Ricciardo, who otherwise would surely have won.

Victory for Hamilton in the following race, in Canada, where he was lucky to escape penalty after elbowing Rosberg aside at the first chicane, and Lewis seemed on the march. The natural order of things – a dominant Hamilton showing the way to a subservient Rosberg – was being restored.

Sure enough, consecutive victories in Austria, Britain, Hungary and Germany edged Hamilton clear of Rosberg in the points for the first time all season. For the reigning world champion, it was the perfect way to go to the four-week mid-season break. Normal service had been resumed.

But then things changed once more, as Rosberg bounced back to win the next three races. And even while he could do no better than third in Malaysia, he still managed to increase his points lead afterwards. That was because Lewis’ car was a smoking mess on the side of the track after it had suffered a major engine failure.

If Rosberg does turn out to be the 2016 world champion, this is the point when things finally turned his way. Hamilton had dominated the Malaysian Grand Prix from the moment they arrived in Kuala Lumpur; he was cruising to an effortless victory when his engine suddenly went bang.

Disaster for Hamilton in Malaysia as his engine fails while he held a commanding lead

It was the lowest ebb in Hamilton’s already topsy-turvy season, and in more ways than one. After the race, with the adrenalin still not having subsided, Lewis seemed unable to accept his fate when questioned on the engine failure. Why was it always his Mercedes engine that failed, he wondered out loud? He went further. Something ‘just doesn't feel right’ about it, he said, and that ‘someone’, some ‘higher power’, ‘doesn’t want me to win this year’. Later, when asked to clarify exactly what he meant by ‘someone’ (and whether he actually really did mean someone at Mercedes), he obliquely referred to the ‘man above’.

It was a bizarre distraction that was in stark contrast to Rosberg’s feet-on-the-ground, one-race-at-time mantra, and a clear sign of the pressure Hamilton was feeling.

If that wasn't enough, at the next race Hamilton found himself in a public spat with the Fleet Street press. Snubbing the British scribes at a press conference while he busied himself posting on social media prompted headlines such as ‘all snap and no chat’, among other derogatory witticisms. But he did not see the funny side of it, and hit back at the press, boycotting them entirely. Their response was predictable: pretty much all-out war. Lewis was the ‘Berk in the Merc’, one wrote; elsewhere he was described as ‘fragile’ and ‘in meltdown’, a man with ‘bottomless reserves of childishness’.

It is said, by Hamilton himself and others, that Lewis is at his best when under pressure. There was even a theory that Hamilton had manufactured the Fleet Street barney as a deliberate means of putting himself under the kind of pressure he apparently needs to conjure a winning performance. While that’s probably paying Hamilton too much credit, he certainly came out fighting in Japan and in Texas. The Japan race did not go his way (if only because of a poor start – something of a hit-or-miss deal these days in F1) but in Texas he was supreme. Rosberg simply had no answer to Hamilton’s pace.

On the evidence of the American race, Lewis will be hard to stop in the remaining three rounds. But is too late? Has the damage already been done? Even if Hamilton wins all three races, Rosberg’s points margin is such that Nico only needs to finish second in each one to claim the crown.

Will Rosberg still be leading Hamilton at season's end?

With those calculations in mind, what Hamilton needs is help from outside the Mercedes team, as much as from within it. Barring Rosberg’s engine succumbing to a ‘higher power’ (or simply failing of its own accord) between now and the final round at Abu Dhabi, it could be that Hamilton’s only chance is to win all three races and pray that someone else is also good enough to beat Nico on the day.

The circumstances under which Lewis Hamilton goes to Mexico this weekend are thus highly unusual. For one, he finds himself in the unaccustomed position of trying to wrest the world championship away from his team-mate. Secondly, he’ll be hoping that one or two of his rivals outside of the Mercedes fold (or to be more specific, Daniel Ricciardo and Red Bull team-mate  Max Verstappen), are faster than everyone – except the number 44 Mercedes.