Massa, Hamilton and Kubica are all in with a shout of the F1 title
The Formula One world championship is poised for a thrilling climax with three drivers in with a chance of winning with two races to go.
Lewis Hamilton of McLaren heads into Sunday's race in China with a five-point championship lead over Ferrari's Felipe Massa, with BMW Sauber's Robert Kubica a further seven adrift.
On paper, Hamilton should be a strong favourite, and Kubica - whose car is off the pace of the Ferrari and McLaren - should have no chance.
He is a target for everyone to make it as difficult as possible for him, and he's brought it all on himself
Runner-up, 1982 F1 world championship
But the Englishman's position is not as strong as it might at first appear.
And after a season of topsy-turvy results and high-profile errors, it is clear anything could happen - especially when Hamilton appears to have more enemies out on the track than he does in the title battle.
We assess the positions of each of the three contenders.
HAMILTON - 84 points
Despite being in the lead, Hamilton has arguably the most difficult task of all in China this weekend, in that he has the pressure of being the man with most to lose.
He has led the championship for longer this season than any of his rivals - and has occupied the top slot since winning the German Grand Prix in July, having shared it with Massa and his Ferrari team-mate Kimi Raikkonen after the preceding British race.
For sure the pressure is there - you try to avoid it and sometimes it just gets you
But in recent races Hamilton has given every indication that he is quite capable of throwing it all away.
A series of errors - most recently at the start in Japan last weekend - have cemented the impression that he is vulnerable to mistakes under pressure - a reputation that began to form when he lost the title last year.
John Watson, runner-up in the world championship in 1982, agrees that Hamilton has to find a way of removing the impetuousness that looks in danger of wrecking his chances again.
The Northern Irishman says there is no question about Hamilton's "flair, talent and courage", only his mentality - and describes Hamilton's driving at the start in Fuji on Sunday as "stupid, ill-judged and immature".
"Lewis doesn't have to win, he just needs to finish second to Massa, but that is one part of his personality he has to work on," Watson says.
"He has yet to fully establish his ability to deal with the greatest level of stress and pressure. Part of that is that he has only ever been in a winning car.
F1 POINTS SYSTEM
First place - 10 points
2nd - 8pts
3rd - 6pts
4th - 5pts
5th - 4pts
6th - 3pts
7th - 2pts
8th - 1pt
In the event of a tie, positions are decided on results countback - the driver with most wins would be champion; if wins are tied, it is the driver with most second places, etc
"What I'm concerned about is he seemed [in Japan] to delete his brain from its normal programme and put it onto self-destruct."
According to Watson, there is another concern for Hamilton - the limited help, or even active hindrance, he can expect from his rivals.
Team-mate Heikki Kovalainen has rarely been in a position to take points from the Ferraris this season, whereas Massa can expect much more active help from Raikkonen.
At the same time, the Toro Rosso cars, which use Ferrari engines, are competitive enough to be a nuisance - as is Renault's Fernando Alonso, who has no wish to help McLaren after falling out with them while Hamilton's team-mate last year.
Finally, Hamilton has made himself unpopular with his rivals by engaging in driving they consider to be over-aggressive on a number of times this season.
"It's all very well to drive like [Ayrton] Senna and [Michael] Schumacher," Watson says, "but they were a bit further down the road when they did it.
"The thing that's going to beat Lewis is he's not just got to race Massa, he's racing the entire field.
"He needs to stop sending those signals out [where he has] to have a field of competitors, 18 of whom are against him.
"He must be a target for everyone to make it as difficult as possible for him, and he's brought it all on himself."
Hamilton can win the title in Shanghai if:
He wins, with Massa lower than fourth; he is second, with Massa lower than sixth; he is third, with Massa out of the points, as long as Kubica does not win.
MASSA - 79pts
Massa's situation is simpler than Hamilton's - he knows he must beat the McLaren driver in China to have any realistic chance of winning the championship at the final race in Brazil on 2 November.
That means the Brazilian does not have to worry anywhere near as much about weighing conservatism against aggression.
Massa, Hamilton and Kubica are staging a three-way shoot-out
Massa has led the championship this season - after a somewhat lucky victory in the French Grand Prix, earned when Raikkonen's exhaust broke.
But generally he has been in the chasing role. In that sense, the title is Hamilton's to lose, rather than Massa's to win.
"He is in a much more comfortable situation," Watson says. "He's got nothing to lose."
There are those in F1 who have difficulty comprehending the possibility of Massa becoming world champion because he is not considered to be an out-and-out top-line driver.
But Watson says: "Other than in the wet races, he's done a good job overall. He's probably the most improved driver, and if he can find himself in a situation where Raikkonen can help him, then he will."
What Massa needs to do:
Massa cannot win the title in China. He will extend the battle to the final race at Brazil as long as he does not drop more than five points to Hamilton.
KUBICA - 72pts
If Massa has nothing to lose, that goes double for Kubica, who needs some major misfortune to befall his rivals to have a chance of emerging from Brazil as champion.
In many ways, the Pole has been the driver of the season. He has been more consistent than anyone, and has got more out of his equipment than any other driver in the field with the arguable exception of Alonso.
Kubica, an old rival of Hamilton's from their days in karting, was leading the world championship after his victory in Canada in June, which was the climax of a quite superb start to the season from himself and BMW.
Hamilton harmed his own chances with this wild move in Japan
But in the wake of that win BMW took the surprising decision to focus most of their energy on their 2009 car, reasoning that they were not competitive enough to be realistic title contenders this year.
It was a logical decision, albeit one that did not go down well with Kubica, but it appears now to have backfired because of the unexpected lack of consistency and mistakes that have emanated from Hamilton, Massa and their teams.
Following Renault's resurgence, BMW now have what appears to be the fourth quickest car in the field.
And, as Alonso puts it, winning the world championship in that position would be "quite difficult because [with] the performance of his car [it] will be difficult to recover 12 points".
What Kubica needs to do:
Kubica needs to come away from China no more than nine points behind the leader of the championship to still be in with a chance in Brazil. So he needs to beat Hamilton by more than two points and lose no more than two to Massa. If he is 10 points or more behind either he cannot win the title because even if he won in Brazil with the others not finishing he would lose on win countback.
Hamilton is aware he holds the destiny of the title in his hands, and insists that "the most important thing is to get some points" in China on Sunday.
But he will still be anxious to make as much of the weekend as he can - not least because Ferrari have been very strong in Brazil in the last two seasons.
If Lewis blows it again this weekend, if it goes to Brazil [with Massa ahead], it will be Massa's championship
He will therefore not want his lead to be reduced - because if he is four points or less ahead of Massa after China, and Ferrari were to score a one-two in Brazil, that would make Massa champion.
And that is where his ability to keep a rein on his natural aggression will be most severely tested.
As Hamilton himself puts it: "For sure the pressure is there. You try to avoid it and sometimes it just gets you."
Watson says: "Lewis should do it - he's got a five-point advantage and he has a fast car.
"His natural speed, his qualifying ability - all the known factors say he should do it. The biggest concerns are the unknowns - the other competitors.
"It will come down to his own mind. I'm sure he's not going to do the same as he did in Japan last weekend.
"There are enough people at McLaren to sit him down and say: 'Consolidate.' He doesn't need to beat Massa. He just needs to stay ahead.
"But if he blows it again this weekend, if it goes to Brazil [with Massa ahead], it will be Massa's championship.
"All I would like see him do is use the brain he's got in an active way and stop trying to do things a Formula Ford driver would do.
"He can win it but he's just got to use his brain."