Felipe Nasr has admitted that he struggled for pace in his Sauber throughout the Malaysian Grand Prix weekend.
After a fifth-placed finish at the season-opening race in Australia, the Brazilian rookie briefly came into contact with Kimi Raikkonen before ending up outside the points at Sepang.
However, Nasr has suggested that both he and the team are unsure as to why his Sauber lacked performance.
"It was overall a difficult weekend for me," Nasr told reporters. "I was struggling to find a good set-up for the car. We need to reflect and understand why we didn't have enough pace.
"The race itself was not easy, as I had contact early on with Kimi. I should have avoided this incident, but it can happen sometimes when we are racing."
Nasr's teammate Marcus Ericsson spun out early on and beached his car in the gravel at turn one, leading to the safety car being deployed, which worked to the advantage of race winner Sebastian Vettel.
