On the face of it, Lewis Hamilton should be able to stroke home to the World Championship in next weekend's Brazilian Grand Prix.
All he needs to do is finish fifth, regardless of how well his title rival Felipe Massa does. But within the McLaren Mercedes camp there is the memory that last year their man went to this same race with a seven-point lead – just as he does now – yet came away the runner-up as Ferrari's Kimi Raikkonen stole the prize at the eleventh hour.
"Of course, we are keenly aware that the World Championship could be won or lost by a mechanical failure," the team's chief operating officer, Martin Whitmarsh, said.
"As a result, we are leaving no stone unturned in our efforts to minimise this possibility. That meant consciously turning down Lewis's engine on the run to the flag in China in order to give him plenty of engine life for Brazil."
Normally, drivers are given a joker which allows them one "free" engine change during the season that avoids a 10-grid place penalty, but the regulations do not allow Hamilton to play in Brazil. There his engine will be on its second race after winning in China, and his gearbox on its third. But Whitmarsh said they do not envisage problems.
"We can afford to be more conservative than normal in our approach to Lewis's race, but we are still pushing to win the Constructors' Championship, and it would be wrong of us to overlook this," said Whitmarsh.
Unless the Briton fails to score, Massa really has to win, something he did convincingly at Interlagos in 2006. And although the odds favour Hamilton, the Brazilian knows that neither of them can take anything for granted.