Valentino Rossi thinks Marc Marquez is "very close to the perfect season", but the Repsol Honda rider disagrees.
Marquez holds a 98-point lead in the riders' standings and can seal his sixth MotoGP title and fourth in succession by scoring two more points than nearest rival Andrea Dovizioso at this weekend's Thailand Grand Prix.
With the Spaniard, who has finished first or second in all but one of this season's races, having a chance to wrap up the championship with four rounds to spare, Monster Energy Yamaha rider Rossi conceded little can be done to stop him.
"For me there are different factors. I think this one is the best season for him in MotoGP together with 2014," said seven-time champion Rossi, referencing the year Marquez won the first 10 races and went on to seal the title.
"From the first season he was very fast but now he is in a moment of his career where he is still very young but also has a lot of experience, so he has reached the top level.
"Always finishing in the top two except for one time in Austin when maybe he did a mistake due to a problem with the bike, I think that this is very close to the perfect season."
Marquez's only failure to finish this season came when he crashed out while leading the Grand Prix of the Americas in April.
The 26-year-old did not agree with Rossi's evaluation of his campaign but acknowledged it has been one of his best seasons in the premier class.
"It is one of my best seasons and it is not perfect, that doesn't exist. But apart from Austin, at the other race tracks I have been very, very happy how we worked with the bike and with the team," said Marquez.
"The team has been focused and I have concentrated more on our weak points and our weak tracks and that is where we have finished second sometimes. But it is not the same as finishing second behind the top guy by five or six seconds, it has been just one tenth.
"At our weak circuits we have fought until the last corners so I am happy. It is difficult to repeat for next year, but we are working to improve ourselves, to improve the performance of the bike and the team and to try to be better and stronger."