Mercedes is expecting a "big challenge" at this weekend's Singapore Grand Prix as it returns the scene of some of its weakest performances in recent years.
Despite winning 51 of 59 races over the last three seasons, Singapore has proved to be something of a bogey circuit for Mercedes and in 2015 it was comprehensively outperformed by Ferrari and Red Bull in an otherwise dominant year. A hard-fought victory last year saw Nico Rosberg beat Red Bull driver Daniel Ricciardo by less than half a second -- Mercedes' smallest winning margin of the season -- but with Ferrari a much bigger threat this year, team boss Toto Wolff is expecting his team to struggle.