Valentino Rossi has lost sixth in the world championship to rookie Fabio Quartararo after falling from eleventh place in the closing stages of Sunday's Japanese MotoGP.

The Italian had qualified down in tenth position, then lost four places on the opening lap and could only mount a minor recovery by the time he suffered his fourth DNF of the season.

Countryman Andrea Iannone (Aprilia) was the only other rider to fall.

"I started quite bad, not in the first corner, but after that I was in the middle of the chaos and lost time," said the Monster Yamaha rider. "Then my pace was not good enough to recover positions fast. I managed to recovered a few, but I was not very strong.

"On some laps my pace was not so bad, but everybody was fast so it was very difficult to recover from behind. And at the end – I haven't seen the data yet – but I think I made a small mistake in Turn 1, closed the front and crashed.

"But anyway it was a difficult race."

In an effort to get back on terms with team-mate Maverick Vinales and Petronas Yamaha star Quartararo, Rossi switched away from the new carbon fibre swingarm and double exhaust this weekend.

The Doctor also experimented with braking technique but, while feeling he had a more consistent pace than in the previous races, still wasn't fast enough.

"I think this time I was stronger compared to the last two races but I started too far back. My potential was to be with Rins [7th] and Crutchlow [5th], I had the same pace as them," he said.

"My pace was quite constant until the end, so for that reason we were going better. But anyway, it's a bit of a difficult moment becuase in the last races we are not fast enough. We don’t have the speed that we want.

"We have to be faster to be able to fight for better positions."

A fourth podium in the last six races has put Quartararo 18 points ahead of Rossi, with Petronas team-mate Franco Morbidelli (tenth) now the only Yamaha rider behind Rossi in the championship standings.

The good news for Rossi is that he heads straight to one of his favourite tracks, Phillip Island in Australia, where he will attempt to end the now 13-race podium drought.

"Phillip Island is always great, because the track is one of the best," he said. "But we will have to look at the data and see if we can understand how to be faster there."