The Malaysian Grand Prix this weekend is only the second race of the season, but it is a very important race in the title fight between Mercedes drivers Lewis Hamilton and Nico Rosberg.
Hamilton's victory in the season-opening grand prix in Australia was his seventh win in eight races, stretching right back to the Italian Grand Prix in September last year.
At this early stage of the season, it is less about points between Hamilton and Rosberg than it is about confidence.
Hamilton is on a roll and his confidence is sky-high. Rosberg needs to kick that into touch somehow - and quite quickly. If he doesn't Hamilton's confidence will grow and grow, and the points gap will keep extending and it will be hard for Rosberg to get it back.
How does Rosberg do that? Probably by getting under Hamilton's skin a little - just as he did with the incident in Monaco qualifying, when his going off the track prevented Hamilton from beating Rosberg to pole.
That destabilised Hamilton a bit and Rosberg went on a run for the next few races.
When Hamilton is strong, he is very, very strong. But he can waver, and when that happens he can give points away left, right and centre - just as he did last summer.
Rosberg drove very well in Australia, in both qualifying and race; his problem was that Hamilton was just that bit better, and did not make any mistakes.
When Hamilton makes a mistake, he tends to amplify it. Rosberg has to be there all the time, just waiting for that to come. And it will do at some point.
Its going to be tough for Rosberg, though, there is no doubt about that, and heading into this weekend he cannot take any encouragement from last season, because in 2014 Malaysia was arguably Hamilton's most dominant race.
It is highly likely to be another one-two for Mercedes.
They probably have an even bigger advantage at the start of this season than they had at the end of last, and it looks like they have improved in pretty much all areas.
Malaysia is a demanding circuit, with high-speed sections, slow-speed sections and long straights. Mercedes have everything you need - good aerodynamics, good traction and good straight-line speed.
Alonso back in the saddle
It looks like Fernando Alonso will be back in the cockpit in Malaysia, for his first race for McLaren this year, pending an official FIA medical check.
Passing that is not necessarily a given, because concussion is a hot topic in sport at the moment.
Having said that, Alonso would not have flown to Malaysia if the medical advice he has been given was in any way inconclusive because it is one of the most difficult races on the calendar.
The circuit is not the hardest physically, but the race takes place in very hot and humid conditions.
A driver's body temperature and heart rate goes very high there, and the effects of concussion are compounded in those circumstances.
Alonso will have to go through what's called an impact test, which is basically an online test for reaction and co-ordination.
One of the reasons drivers are advised not to return until they are fully recovered from concussion is that if you do exercise while you still have it, your powers of processing drop off significantly.
One has to assume that all evidence of his concussion has now gone, but even so it would not surprise me if he found the whole weekend quite tiring and had a few headaches during the course of it.
It can take a surprisingly long time to get completely back to normal after concussion - I remember looking back three months later and realising that although I was able to drive and race without problem, I was still not 100%.
I don't think it will affect his speed at all. But after a bang on the head it can be tougher to concentrate and to regulate your body, because it is still recovering at its most central point, the brain.
From McLaren's point of view, it is important to get Alonso back.
For one thing, it draws a line in the sand after all the speculation about what happened to cause the accident and the mishandling of the aftermath by McLaren.
For another, he is effectively the team leader, and it enables them to get his read on where they are after a very difficult weekend in Australia, where they were the slowest team by far.
Alonso on his own won't bridge the gap to the rest of the field and I expect them to struggle even more in Malaysia than they did in Australia, because they were already concerned about heat management in Melbourne and that is only going to get worse in Malaysia.
Big problems at Red Bull
Red Bull, so dominant until relatively recently, had a nightmare start to the season and it looks like they have gone backwards over the winter.
The team feel they have gone forwards with the car, but the woes of their engine supplier, Renault, have increased.
The engine has not improved in performance at all from 2014 to 2015, and that relationship is fraying badly.
Red Bull team boss Christian Horner said Renault were "a bit of a mess". That is pretty pointed.
It is very rare to hear someone in F1 speak as directly as that about a partner, and I can only imagine it is to try to get the parent company of Renault to take this very seriously, to force it beyond a racing agenda and have it discussed at higher levels.
There were a lot of meetings between Red Bull and Renault over the Australian weekend, which were pretty long and when the people came out they looked pretty hot and flustered.
With the progress Ferrari have made - much of which is down to the engine improving - and Williams stepping up, Red Bull do not have great prospects.
Malaysia could well be an even more difficult weekend for them than Australia. That's because one of their biggest problems is the poor driveability of the engine, and that is very important for overall performance at Sepang, because it is hard on the rear tyres.
There were strong performances from all three rookies in Australia, the Toro Rosso pair of Carlos Sainz Jr and Max Verstappen and Sauber's Felipe Nasr.
They were neat and tidy and all three would have brought home points had Verstappen not retired.
In many ways, they reminded me of the debuts of Daniil Kvyat and Kevin Magnussen last season, both of whom have gone on to have good results.
In Australia, there was no doubt that Sainz shaded the internal battle with Verstappen, who had garnered much of the pre-race attention because at 17 he is the youngest driver in F1 history.
Sainz qualified ahead and was faster in the race, and may well have finished seventh rather than ninth had he not been delayed by a problem at his pit stop.
But you have to remember that Sainz has a lot more experience than Verstappen.
Last year, he won the Renault 3.5 series, which is very strong. He was racing in British Formula Three in 2012. So he was probably better prepared than Verstappen, even though the Dutchman was initially chosen by Red Bull ahead of him for this season.
But you have to deliver - and that's what Sainz did.
Verstappen was impressive nonetheless. He made a mistake at Turn Five on his final qualifying lap, and had a big tank-slapper. But the critical thing for me was that he then did not lose any further time over the rest of that lap.
Quite often, an inexperienced guy like that, if they lose time on their final qualifying lap, will then try to make it up over the rest of the lap and end up making mistakes.
Verstappen did not do that, which suggests he had a semblance of mental control and was not over-driving and attacking too much.
Nasr has been labelled a 'pay-driver' because he has brought sponsorship to Sauber, but he is very talented. He won British F3 when it was at its most competitive and has won races in GP2.
Yes, he comes with money, but so did Ayrton Senna and Rubens Barrichello. Most Brazilians do. It doesn't mean they are any less able.
Considering the weekend Sauber had, with the contract row over Giedo Van Der Garde, for Nasr to take fifth, ahead of Daniel Ricciardo's Red Bull, was stunning.
My tip for a dark horse
Watch out for Lotus and Romain Grosjean this weekend.
Last year, when they were struggling with their car, Malaysia was one of their most competitive races.
They qualified decently in the top 10 in Australia, they have the Mercedes engine now, and if Grosjean had not gone out on the first lap, they would have had a very strong points finish.
Team-mate Pastor Maldonado was up there as well, which means the car is driveable. So they could be in for some good points if they have a problem-free weekend.