Valentino Rossi reckons his bike suffered from set-up problems in tonight's Qatar Moto Grand Prix and that his Fiat Yamaha team must forget what they had learned while using Michelin tyres.
The seven-time champion demanded and obtained a switch to Bridgestone rubber at the end of last year, after being soundly beaten to the title by Casey Stoner's Ducati fitted with the Japanese tyres.
This opening round of the 2008 season saw, however, another win by Stoner, while second went to Rossi's rookie teammate Jorge Lorenzo on equal machinery fitted with Michelin tyres.
Rossi finished in a disappointing fifth place.
"I think we aren't ready yet and the set-up of our bike isn't optimal," the Italian told Italia1 television. "In the first laps we go well, but then the bike starts moving a lot. I think it's a set-up problem.
"We must forget all the settings we had over the past years and start over again to have the bike working differently. I'm really quick under braking, but I'm slow around the corners and I struggle.
"I think we'll need to set-up the bike in a completely different way, because these tyres have to be used in a very different way. But no more than a month ago we flew in Malaysia, we were really quick, and Stoner is up in front with the same tyres.
"So we must only understand the way to use them. We must do it quick, we need to be more reactive and quick, and most of all we must forget how we've used the bike up to now."
Rossi held the lead of the race for three laps, then after being overtaken by Stoner and Lorenzo kept Repsol Honda's Dani Pedrosa behind for five laps, and finally held off Andrea Dovizioso until the last lap, when the rookie made a move that stuck.
"We knew it would be a tough race," continued Rossi. "I had hoped to get on the podium, and I tried to keep Pedrosa behind in every way but there was nothing I could do.
"But as it happened in the warm-up already, when I have so much grip at the beginning, I know I have to pay for it a bit later. We changed the tyre compared to this morning, but the problems remained the same, so there's something we have to do differently.
"There are also some positives, our bike has a strong engine. I started well and rode well especially in the first laps. But we got beaten, so we must accept that and try to understand why."
Asked if the set-up problem may turn out to be even bigger on circuits where he hasn't tested yet, Rossi replied: "That's impossible to say, in the sense that this is the track where we've had the most problems with Bridgestones, already in the tests. At Jerez we went better, and in Malaysia we went very well."
He added: "These rivals are very strong and young, but I think that, once we're sorted, we'll be able to easily fight with them."