Kimi Raikkonen admits he had "a difficult day" as he struggled with set-up during Friday practice for the Russian Grand Prix.
The Finn was fourth quickest in both Friday sessions but over a second slower than Lewis Hamilton in FP2 despite using the supersoft tyre. Raikkonen had to compensate for Sebastian Vettel's lack of running during the second session and he says he couldn't get a good set-up to feel happy with his car.
"It was a difficult day," Raikkonen said. "Nothing seemed to work as well as I wanted. One of those days struggling to make the tyres work and making sense out of the set-up. Apart from that everything was more or less okay."
Ferrari is using an upgraded power unit this weekend in Russia having spent three development tokens and Raikkonen is sure it will provide an improvement even though he would not compare it to the old specification.
"It is a new engine. Comparing a new engine to the same (old) engine is very difficult to say. It feels different in different places and different days . It works well, and we wouldn’t use any new parts - engine or any other - if we don’t think it is a good thing."