Lewis Hamilton fears he might have the first winless season of his Formula One career because he thinks Max Verstappen and Red Bull are "almost unbeatable".
Seven-time world champion Hamilton has won at least one race in every season stretching back to his rookie year, 2007.
Mercedes has crept closer to the front over the course of this season but has never been in title contention.
With six races left, Hamilton knows he is running out of time to extend his record.
"We have to be realistic. That Red Bull is almost unbeatable," Hamilton said.
"It's going to take some real doing to beat that car.
"Performance-wise we have not caught them, and we don't have upgrades coming to enable us to overtake them. So it's going to take some fortune going our way to win.
"It's not impossible, because we could have beaten them in Budapest.
"But Max is generally chilled at the front, so you can never tell their true pace."
Verstappen's recent form has been so dominant he has an outside shot of wrapping up the championship at the next race, the Singapore Grand Prix on Oct. 2.
Verstappen is not just closing in on the title. He has won 11 races this year and has six more events to pass the current record of 13 in one season, held jointly by Michael Schumacher and Sebastian Vettel.