Hamilton made a poor start, ran off the road at the first corner and was tipped into a spin by Massa on lap two.

Both were given penalties for different incidents but Massa recovered to take seventh and cut Hamilton's lead to five points with two races left.

Hamilton, his car damaged by Massa, was 12th and out of the points.

Massa finished eighth on the road, but was promoted to seventh when Toro Rosso's Sebastien Bourdais was penalised 25 seconds, demoting him to 12th, for a collision with the Brazilian on lap 51.

Hamilton is still in a strong position but the Englishman will have to cut out the mistakes that have characterised his season if he is not to lose the championship for the second year in a row.

"What can I say? it was a bad day, I'll move on to next week in China," he said.

Hamilton's problems began at the very start of the race as he got off the line slowly from pole position in his McLaren and then went too far in trying to make amends at the first corner.

He left his braking too late trying to prevent Ferrari's Kimi Raikkonen taking the lead and, with smoke pouring from his locked tyres, took both of them off the track.

The move would earn Hamilton a penalty for forcing another car off the track, but it also demoted him to sixth place, right behind Massa.

The Englishman tried to pass the Ferrari into the Turn 10/11 chicane on the second lap and the two cars ended up colliding.

Massa left his braking too late trying to fend Hamilton off into the initial right-hand part of the corner.

That put him off line on the outside and, trying to retain the place, he dived over the kerbs through the left-handed part and tipped Hamilton into a spin as he rejoined the track.

Hamilton had to sit and wait for the entire field to pass before he could rejoin the race, and he immediately called into the pits for new tyres to replace the ones he had badly flat-spotted at the first corner.

Massa was given his own penalty for causing that collision, and, once they had taken their drive-through penalties, the two title rivals ended up at the back of the field - with Massa a few seconds ahead.
Massa was penalised for this - but still cut Hamilton's championship lead

The chaos among the drivers of the leading teams left Kubica in the lead but he lost it to Alonso when the Spaniard made his first pit stop a lap later than the Pole.

Alonso said he asked the team to get him out in front of Kubica but doing so meant he had four laps' less fuel than the BMW for the middle stint of the race.

The team lost no time in telling Alonso that he had to "sprint like hell" to win the race.

The double world champion did exactly that, pulling out a lead of more than 12 seconds in his 25-lap second stint.

That put him completely out of Kubica's reach, and the BMW driver was left to fend off Raikkonen.

It was one of the Spaniard's greatest races and secured him and Renault an unexpected second win in a row.

"I cannot believe it right now and back-to-back wins is a great feeling. It is completely amazing."

The world champion rejoined from his final stop just behind Kubica but, although he pressured the BMW hard for the next few laps, the Pole was able to fend him off and eventually build a small cushion for the last few laps.

Nelson Piquet finished fourth for Renault, with Toyota's Jarno Trulli next, followed by the Toro Rossos of Bourdais and Sebastian Vettel and Massa.

Rubens Barrichello did best of the local drivers with 13th place for Brackley-based Honda, while Jenson Button was 14th.

Massa, the fastest man on the track in the closing stages of the race, lost ground in the incident with Bourdais but recovered to grab eighth on the road from Red Bull's Mark Webber on the penultimate lap.

Final result of Japanese Grand Prix:

1 Fernando Alonso (Spa) Renault one hour 30 minutes 21.892 seconds
2 Robert Kubica (Pol) BMW Sauber 5.2 seconds behind
3 Kimi Raikkonen (Fin) Ferrari at 6.4secs
4 Nelson Piquet (Brz) Renault at 20.570secs
5 Jarno Trulli (Ita) Toyota at 23.767secs
6 Sebastian Vettel (Ger) Toro Rosso-Ferrari at 39.207secs
7 Felipe Massa (Brz) Ferrari at 46.200secs
8 Mark Webber (Aus) Red Bull-Renault at 50.811secs
9 Nick Heidfeld (Ger) BMW Sauber at 54.120secs
10 Sebastien Bourdais* (Fra) Toro Rosso-Ferrari at 59.000secs
11 Nico Rosberg (Ger) Williams-Toyota at 1:02.096
12 Lewis Hamilton (GB) McLaren-Mercedes at 1:18.900secs
13. Rubens Barrichello (Brz) Honda one lap behind
14. Jenson Button (GB) Honda at one lap
15. Kazuki Nakajima (Jpn) Williams-Toyota at 1 lap
R Giancarlo Fisichella (Ita) Force India-Ferrari 22 laps
R Heikki Kovalainen (Fin) McLaren-Mercedes 16 laps
R Adrian Sutil (Ger) Force India-Ferrari 8 laps
R Timo Glock (Ger) Force India-Ferrari 6 laps
R David Coulthard (GB) Red Bull-Renault 0 laps

* Bourdais penalised 25 seconds for collision with Massa

Key: R = retired