Felipe Massa conceded Ferrari is faster than Williams after losing out to Sebastian Vettel in their fight for a podium finish in the Australian Grand Prix.
The Brazilian lost time behind Red Bull's Daniel Ricciardo and was passed by Vettel for third on lap 20, eventually finishing in fourth position less than four seconds behind.
Williams driver Massa said Ferrari had the quicker car, but he reckons he could have kept Vettel behind if not for the time lost behind Ricciardo.
"It's true that Ferrari had a little bit of an advantage on the pace - maybe a couple of tenths, it's difficult to be sure about it - but maybe they had a little bit better pace," said Massa.
"But being in front was the best I could do to fight because it's not an easy track to overtake.
"So to lose the position like that is not nice, it's a bit disappointing but it's just the first one, we're still in the fight.
"We know that they are better, they are more competitive so the championship is not easy. We are in the fight but it's always good to start with more points."
Big engine progress
The Williams driver believes Ferrari has made huge progress on the engine side, as proved by the fact that both the Ferrari-powered Saubers had a strong weekend.
"Yeah, 100%," he said when asked if Ferrari's engine had improved. "Who finished fifth? Sauber. From where they were last year and not having any money to put in the car.
"It's a team that doesn't invest so much in the team and they just improved a lot which I think is coming from a different part.
"Surprise? No, because I saw in the tests and I saw here on Friday. So it's not a surprised; Mercedes is for sure even better than everyone expected."