How quickly things can change. At Phillip Island a week ago, Valentino Rossi was being feted for his 400th Grand Prix start against a background of concern over the nine-time champion’s pace.

Sitting seventh in the championship with 153 points, behind both Monster Energy Yamaha teammate Maverick Viñales and Petronas Yamaha SRT rider Fabio Quartararo, questions were being asked whether it was time for Rossi to retire.

And yet a year ago, at Sepang, Rossi came within four laps of winning the race, or at least taking the race down to the wire with Marc Márquez. The Italian crashed out at Turn 1, washing the front out and handing victory to his arch rival. But the race was as clear a sign as you could get that Rossi was still competitive, still capable of winning races.

Jorge Lorenzo finds himself in a similar situation. At Phillip Island, he had one of the worst races of his career, finishing 66 seconds behind his teammate, the winner Marc Márquez.

Lorenzo is on his way out, the media and fans said, he can’t ride the Honda. Yet in November last year, at the Jerez test, Lorenzo was fifth fastest overall, a tenth of a second behind his teammate, and 0.160 slower than fastest rider Takaaki Nakagami.

It is clear that circumstances matter. Sure, riders lose their pace over time, start to slow down with age, take more time to adapt to one bike rather than another. But riders don’t go from winning races one year to being mid pack or much worse the next of their own accord.

There is more going on than meets the eye – in Rossi’s case, a search for speed and the balance between grip and tire life, in Lorenzo’s, a return from a vertebrae injury combined with a bike he still doesn’t trust completely. So changing circumstances may help change their fortunes.

MotoGP heads 6400km north for the final leg of the Pacific flyaways, and the penultimate race of the season. The contrasts between Phillip Island, where the paddock has just departed, and Sepang, where they have just arrived, could hardly be greater.

Phillip Island famously has four seasons in one day, though all too often, those seasons are winter, spring, winter, and winter. Sepang has two seasons in one day: hot and humid, and hot and pouring with rain.

The rain can come as a blessed relief, though, in what is undoubtedly the toughest race of the year. “I think this will be the toughest race of the year,” Danilo Petrucci said. “Yesterday I went out for a run, and I was lucky that in the middle of the second lap when I was running that a thunderstorm has arrived, and I asked to the rain if it can come on the second lap of the race!”

“Joking apart, it helped me a lot yesterday. The last two years it has been wet, and it’s tough anyway, because in the wet, the problem is not the temperature, but the humidity, and it’s very difficult to breathe. You don’t breathe oxygen, you breathe oxygen and water. Last time we rode here in the dry was 2015, and the race was very, very tough.”

So there’s your choice: breathe oxygen and water, or struggle to breathe at all.