Lewis Hamilton concedes it has “not been a great year” for Mercedes regarding the development of its Formula 1 engine.

Mercedes has fallen behind its chief rival Ferrari in terms of outright power and straight-line speed performance following a design concept change with its W10 challenger, enabling the Scuderia to edge clear as the new engine benchmark in 2019.

Ferrari made gains with its latest power unit upgrade at Monza amid a resurgent run of form following the summer break, while Mercedes’ own engine update - introduced at Spa - failed to bring the same level of competitiveness.

Speaking following the Japanese Grand Prix, Hamilton admitted Mercedes has not been able to match its high expectations with its engine performance this year.

“I think it’s not been a great year for us in terms of the great issue, in terms of our engine development,” Hamilton said.

“I think it’s been a really hard time for the guys, they’ve been working as hard as ever but it’s just not been as successful in that department.

“Plus it’s quite draggy but we’ve had great reliability and hopefully that remains the same and that’s still something to be really proud of, of course.”

Hamilton, who was unable to overtake Charles Leclerc in Belgium and Italy and Sebastian Vettel in Japan, spoke of the difficulty in passing Ferrari’s cars even with the aid of DRS and fresher tyres.

“I got in the tow of Sebastian [Vettel], the tow with DRS and maximum power and everything… it’s incredible how quick they [Ferrari] are," he explained. 

“It makes it very, very difficult, even if you’ve got the advantage of the tyre but I think it’s cool anyway, it provides interesting racing.

“We have, obviously, still won the Constructors’ championship but we’ll push to try and maybe reduce the drag a little bit but also increasing power for next.

“So they’re fully onto it and I have all the confidence in the world that we’ll be able to make some sort of step into the next season.”