By Steve Parrish BBC motorbikes commentator

In Portugal, Rossi looked as nervous on the track as I've ever seen him Steve Parrish

When Dani Pedrosa knocked his Honda team-mate and World Championship leader Nicky Hayden off his bike at the Portuguese Grand Prix it was the closest I've ever come to saying an expletive live on the BBC.

It was another truly incredible moment of a sensational season.

Valentino Rossi now leads the championship by eight points going into the final race in Valencia having been 51 points adrift just six races ago.

Pedrosa's cataclysmic error left Hayden in tears and I'm not surprised.

There was no malice intended by the young Spaniard when he skidded into Hayden on lap five in Estoril, but the ramifications were major.

It was a monstrous, monstrous mistake by him, although sometimes we all forget that under the helmet and leathers he is still only 20 years old.

He may have a lot of racing experience but the exuberance and impetuousness of youth got the better of him.

I feel extremely sorry for Hayden as that was probably his biggest and best opportunity to win the world title.

Of course he can still win it, but he is now playing catch up against the might of Rossi, which is never an ideal position to be in.

Valencia MotoGP Live: Sun, BBC Two, 1235 GMT BBC Interactive: Sat, qualifying, 1255 BST Sun, MotoGP Extra, 1400 GMT MotoGP on the BBC

However, the Italian admits himself that he is under a lot of pressure as he hasn't got a very good record in Valencia.

In Portugal he looked as nervous on the track as I've ever seen him.

You could sense the monumental moment between the two Honda drivers had got to him.

He was riding very cautiously, which was the right decision in the circumstances as could easily have been taken out himself.

He took the safe option, but being pipped on the line by Tony Elias could cost him on Sunday.

If he does win the World Championship after the season he has had it will rank up there as one of his greatest triumphs and it will be something we would always talk about and remember.

Tactically, he needs to get qualifying done and out of the way to see where he is on the grid and then keep a very close eye on what Hayden is doing.

If the American goes streaking off into the distance you will see Rossi going streaking off after him.

But Rossi will not bust a gut to win the race, he will be sensible enough just to track Hayden.

As for team orders, Honda will not say anything to Hayden as he knows what he needs to do, but they will say to Pedrosa to stay in between Hayden and Rossi.

Whether he can do that is another matter.

The Valencia track is very tight and twisty and it only has one straight, which makes for fast and furious racing.

You need a bike that is agile and has a good turning capability.

I wouldn't say anyone has a particular advantage so it should be unbelievable to watch.

Prediction: 1. Melandri 2. Hayden 3. Rossi