SPA-FRANCORCHAMPS, Belgium -- Nico Rosberg has revealed Mercedes has been struggling for performance throughout the Belgian Grand Prix weekend and only just managed to resolve its issues in time to take pole position during qualifying on Saturday.
Rosberg took pole by just 0.149s from Max Verstappen -- the smallest margin it has had over its nearest competitor since Daniel Ricciardo took pole in Monaco -- and the German said the gap in true performance at Spa-Francorchamps has been as close as it looked.
"We have had a difficult weekend up to now, especially this morning [in final practice]," he said. "We were seriously off the pace over one lap, so it really wasn't so easy coming into qualifying but we got the job done in the end.
"We really made quite a few changes on the car going into qualifying and we found the right way. It all came together and I was feeling good, so I'm very pleased about that one."
Asked what the problems were, Rosberg said: "We just weren't quick because it's very hot out there and because the Pirelli tyre pressures are very high here for this weekend.
"So it was just a bit of a different world out there and we really had to change a lot of things and adapt, so it was great to see how we managed to turn it around and get there eventually just in time for qualifying. This morning in FP3 we were still quite a long way off the pace still."
Sunday's race presents a good opportunity for Rosberg to close the 19-point gap in the championship standings to teammate Lewis Hamilton, who will start from the back row due to an engine penalty, but the German is not expecting it to be straightforward.
"Well, happy to be on pole but the only thing is it's going to be a very challenging race because the tyres are extremely difficult out there this weekend and strategy and everything is going to be very, very interesting.
"I think we're going to see a bit of everything, then with Max being on supersoft and Kimi on soft there's going to be a whole load of things going on so it will definitely not be an easy one."