Sunday's 1,000th race is live on the BBC Sport website and 5 live from 07:10 BST

Could the Chinese Grand Prix be an epic battle to live up to its status as the 1,000th race in the history of the Formula 1 World Championship? It looks like a decent probability.

Valtteri Bottas, the world championship leader after two races so far this season, heads Mercedes team-mate Lewis Hamilton, the two Ferraris and the two Red Bulls on the grid. Margins are tight, and at this stage it is hard to pick a favourite for victory.

The two Mercedes were separated by just 0.023 seconds in the end, after Hamilton pulled it out of the bag in qualifying, as he so often does, despite struggling for much of the weekend.

But while the gap back to the Ferraris of Sebastian Vettel and Charles Leclerc was a chunkier 0.3secs, that is well within the margin of error given the way performance differentials tend to shrink from qualifying to race.

"It's been pretty close among the top three teams," Bottas said, "so there are many question marks."

Vettel said: "It is a long race and I expect it to be a very tight race."

F1 has been making as much as it can in Shanghai of its landmark moment. There has been a big social media campaign. The teams have been asked to buy in - and have done so, with historic-themed helmets for drivers, and the "F1 1,000" logo dotted around. And there are historic displays of various kinds around the Shanghai circuit.

Which is your greatest F1 race of all-time? Vote for your favourite here

For all that it is possible to nitpick about exactly how many races should be counted, because of the inherent complexities of the sport's history, the fact is that it is the 1,000th race to count for the F1 drivers' championship - and that is a big deal.

It speaks of F1's rich history, its longevity - grands prix actually date back to 1906, long before there was a "Formula 1" or a "world championship" - and most of all its success and popularity that has seen it grow into one of the world's biggest sports. No wonder its American owners - relatively new to F1, and keen to commercialise its heritage as much as possible - want to celebrate it.

It is, as Hamilton said, "great for the sport". But the reality is that, for the drivers, the landmark is not such a big deal. "It's not really much of a moment," Hamilton said, in the same breath. "It's just another race. We're here to win."

But who will?

So far, the two races in 2019 have been markedly different in character. In Australia, Mercedes were dominant and Ferrari struggling. In Bahrain, Ferrari dominated, and Hamilton led Bottas to a one-two only because Leclerc hit engine trouble after disappearing into a race of his own.

In China, the weekend has been different again. While Mercedes have had an edge, it has been a small one. Ferrari have been close, and Red Bull - or at least Max Verstappen - close to them.

All five of those drivers look in with a shout of the podium on Sunday. And the intrigue extends to the different characters of the cars - the Mercedes is quicker in the corners, while the Ferrari has an advantage on the straights. So can the Mercedes build enough of a gap in the first part of the lap to stay out of range on the longest straight on the calendar? And can Verstappen mix it with them?

"A decent start is important," said Mercedes F1 boss Toto Wolff. "It is an interesting constellation that we have the two Mercedes in front with both keen to win and then the battle of the generations of the red ones and then Max will be keen to recover.

"So the start will be very exciting - I hope not too much - and then if you have a decent start it is about trying to survive the first two laps."

As for the likely competitiveness of the cars in the race, Wolff said: "We're seeing massive swings from weekend to weekend, even within one team, and it makes this season really interesting.

"Valtteri was in a class of his own in Melbourne, he struggled in Bahrain, but then he has come back here. For Lewis it was the other way around; he had some issues in the race in Australia, but was really strong in Bahrain.

"If you look at Leclerc and Vettel, it's very similar. It makes racing unpredictable and I'm sure we will see an exciting race as well. Our long-run pace looked decent, but we expect a close battle between Ferrari, Red Bull and ourselves."

Ferrari team boss Mattia Binotto said Sebastian Vettel will take priority in the title race ahead of Charles Leclerc

Ferrari battle intensifies

The talk coming into the weekend was dominated by the balance of power at Ferrari, after Leclerc's sensational performance in Bahrain, where he put his four-time world champion team-mate firmly in the shade.

Ferrari team boss Mattia Binotto has again clarified his stance over the weekend, saying: "If there is any 50-50 situation where we need to take a decision, the advantage would be given to Sebastian simply because Sebastian has got most of the experience with the team in F1.

"He won four championships and certainly for us he's the driver who has most probability to challenge for the title."

This stance, though, is not cast in stone, and Binotto has said that if circumstances change "we may change our position, no doubt".

It is also not completely clear what giving an advantage to Vettel means, because Binotto has said the drivers are "free to fight" and "if there is one driver who is certainly faster, he will get the advantage".

This makes the stakes for the Ferrari drivers heading into Sunday's race particularly high - especially for Vettel, who trails Leclerc in the championship and whose position as team leader is clearly under potential threat.

In China this weekend, he has the result he needed, in that he has generally looked quicker than Leclerc, who has had a difficult weekend. The 21-year-old appeared to be lagging a couple of tenths behind - until qualifying, when he as good as matched Vettel.

"I'm annoyed today with myself," Leclerc said. "I did a mistake in the last lap and I shouldn't have done that. It was 0.1 or 0.2secs and it was not enough for pole but enough for the podium.

"But overall there are some positives because [through practice] I was quite lost, with my set-up and my driving, struggling a bit - actually quite a lot - and we did a final change for qualifying and it was better and I drove better and the lap time came."

To get so close after a weekend in which he was not only struggling with the car but also missed a fair chunk of Friday practice with an engine problem was impressive - and a further confirmation that Vettel has a fight on his hands this season.

As for Vettel, he has not yet scored a podium finish this season, and he admitted on Saturday that this "for sure" increases the pressure on him.

From his point of view, the last thing he needs is to finish behind Leclerc on Sunday.

McLaren have won three times in China, the most recent being with Lewis Hamilton in 2011. Source: Forix

Reality check for McLaren

It was not entirely unexpected - certainly not for the team themselves - but this has been a sobering weekend for McLaren.

Coming off the back of a dire 2018, they have had a strong start to the season and had got their cars into the top 10 on the grid three times out of four so far.

In China, though, Carlos Sainz and Lando Norris line up 14th and 15th, positions worryingly reminiscent of 2018.

The reason for this is straightforward. The big weakness of last year's car was rear grip and stability, caused by a fundamental aerodynamic flaw. This year, that has been cured - but now the car's limitation is at the front. And that's the last thing a driver needs in Shanghai.

It is what is known as a "front-limited" circuit - the long corners mean that a car has to have a positive front end if it is to be quick, so front grip is key. Hence McLaren's slip in competitiveness relative to their midfield rivals.

"We knew before coming here that this track could expose our weaknesses more than the other tracks," Sainz said.

It's not all bad news for McLaren - China is close to as bad as it gets on this front. But it explains why McLaren's public utterances have been notable for their humility so far this year.

They knew - and said - they still had plenty of work to do, despite their positive start to the season. And China has proved it.