Lewis Hamilton has said he does not know if Mercedes will be able to solve their slump in form during the last two races of the season.
In the last two races (United States and Mexico), Mercedes have been beaten by their two rivals, Ferrari and Red Bull - despite winning all of the last four rounds before that.
Hamilton admitted that some of his team's loss of pace is "a mystery" but also said that they have understood a lot of it, too.
"It's not always the case that you find all of the solutions," Hamilton explained to RaceFans.net. "I am confident that everyone has worked as hard as they can to rectify it and to understand it. But it might still take this race or even the next race or even the next race before we fully understand it.
"It just points to the fact that there's still always lots of work to do, even at this point of the year, there's still always lots of work to do, even at this point of the year there's still things you can learn and improve, methods that you can apply to next year, particularly, which are going to be quite important. Even though they've not been great races they've been quite a steep learning curve for us."