Felipe Massa on Sunday abandoned his and Ferrari's hopes of winning the world championship this year in the wake of Jenson Button's victory for Brawn in the Spanish Grand Prix.

The 28-year-old Brazilian said that it was impossible for him to overhaul the Briton even if Ferrari produced a superior car for the rest of the year.

"Even if we improve massively and we are three- or four-tenths (of a second) in front of them, they will score points, so forget it," said Massa, who finished sixth between Renault's Fernando Alonso and BMW's Nick Heidfield after running out of fuel.

"Win the championship? I don't think so. We need to be realistic. After five races, they have won four."

Massa's sixth place was his first points-scoring finish this season on a day when Ferrari team-mate Kimi Raikkonen was forced to retire with mechanical problems.

In the title race, the victorious Button now has 41 points out of a possible 45 and has a lead of 38 points over Massa, who was runner-up to Britain's Lewis Hamilton in last year's championship.

Massa added, however, that he and Ferrari were encouraged by their improvements for Sunday's race following their miserable start to the season, during which they failed to score a point in three races.

He said: "We were two-tenths slower in the qualifying, in Q2, and we were four-tenths slower in Q3, because of fuel. It is similar usually in the race.

"I think two-tenths is quite a big difference and today most of the time they were pulling away slowly. That's the real picture so I think we are still a couple of tenths behind the Brawns.

"As to the Red Bull team, I am not sure because I was in front of (Sebastian) Vettel (who finished fourth). So, maybe I was holding him back. I don't know."

Asked about his fuel problems, Massa said they were not due to a team error in calculating his required fuel load, but were instead caused by a problem with the refuelling itself.

Massa said: "We didn't have a problem with the calculations. We had a problem with the machine. But I don't know if the problem was human or the machine.

"We need to analyse what was the problem. It was very frustrating.

"You fight the whole race and then you have to back off. I was already saving fuel in the last run, but it was not enough, so I had to really back off and let Vettel go.

"I lost a position to Fernando (Alonso) and almost to Nick (Heidfeld), so it was quite frustrating for me, but I know that the team made a big step forward this weekend so we have something to build on now."