Valentino Rossi's Saturday surge proved a false dawn as the Italian superstar slipped to eleventh on the final night of 2017 MotoGP testing, in Qatar.

A late set-up breakthrough on the second night had seen Rossi faster than all but dominant Movistar Yamaha team-mate Maverick Vinales.

But while Vinales went on to complete a perfect pre-season by going even faster on Sunday, Rossi lost ground to the tune of 0.45s and nine places.

"Today was more difficult compared to yesterday. We started with the same bike to continue our programme, but unfortunately I didn't have the same feeling and the same speed," Rossi explained.

"It looks like the condition of the track changed a bit and we were unable to improve. I didn't have the same feeling as yesterday and I was a bit slower.

"We put in a lot of effort to go a bit slower."

The Italian also conceded that Vinales' side of the garage has been quicker to learn how to extract the maximum from the new M1, and admits to being 'worried' ahead of the season-opening race.

"It looks like with the bike we have a good potential, because Vinales is very, very fast," Rossi said. "But I think that he and his team are able to understand in a shorter time the way to make this bike at the maximum and we are a bit in delay. So we are a bit worried and we hope that we can be stronger for the first race."

Asked to compare his present situation with recent seasons, Rossi replied: "Two years ago with Bridgestone was a bit better. But especially last year I was very strong. This year we have some more problems. Now we have to speak and try to understand the way to improve and go faster."

Rossi will also go into the new season, at the same Losail circuit from March 23-26, without data from a race simulation, due to his Sunday troubles.

Vinales meanwhile heads for the opening race weekend as the clear favourite, having been quickest in every test since joining Yamaha in November and with multiple race simulations under his belt.

Both Rossi and new signing Vinales are at the start of two-year deals and the nine time world champion denied feeling any unusual pressure for the year ahead.

"First of all it's not my last chance because I will race for two seasons. At least. And after I we see. No, it's the same [as other seasons]... You have to wait and see what happens."

The #46 wasn't the only favourite to have a sour end to pre-season testing with Honda's reigning champion Marc Marquez falling three times on his way to tenth on the timesheets, just ahead of Rossi.

Rossi, who lapped 0.855s behind Vinales on Sunday, was ranked sixth overall on combined times courtesy of his Saturday pace.