Lewis Hamilton has suggested that Mercedes will face a bigger challenge to hold off Ferrari and Red Bull at this weekend's Belgian Grand Prix.
The Silver Arrows finished one-two in both of Friday's free practice sessions, with teammate Nico Rosberg topping the timesheets on each occasion.
However, Hamilton has said that he expects a "close-run thing" with Ferrari and Red Bull come Sunday's race.
He told reporters: "Today was generally a good day - no problems with my car, great weather and a lot of fun out on track. It's not often it stays dry here and that makes it even more enjoyable with the way the track flows through great corners like Eau Rouge.
"It was great to be back out there. The car felt good and it felt very natural to be straight back to business which is a positive sign. Nico is very quick so I have some work to do tonight to see where I can find some time.
"Ferrari and Red Bull also look closer here than they have at past weekends, so it'll be a close run thing and we'll need to be up for the fight."
Sebastian Vettel won his second race for Ferrari when he took the chequered flag at the Hungarian Grand Prix last time out.
