Double world champion Fernando Alonso remained optimistic and surprisingly upbeat Sunday despite seeing his hopes of a good finish at his home Spanish Grand Prix wrecked by engine failure.

Alonso (26), from Oviedo, was forced to retire on lap 35 when his Renault car's engine failed, a puff of blue smoke signalling the end as he pulled up at the side of the track.

As he climbed from his car, he was greeted by a great roar of admiration from the crowd of 115 000 fans and the applause continued as he walked back around the circuit to the pits.

He had qualified on the front row of the grid for the first time this season and managed to follow the two dominant Ferraris during the first part of the race.

He said: "Sometimes it happens to us, and other times it happens to the others. Unfortunately, it was in my home Grand Prix, but in the end I have a good feeling because at least we were fighting with the top cars when in the first races we were so far behind we couldn't even see them."

Despite running in third place before his first pitstop, Alonso said the podium was out of reach, and he reckons he would have finished around sixth place.

"It was going fine. It was just what we expected," he said.

"The podium was impossible. We were going to fight with (Heikki) Kovalainen and (Nick) Heidfeld for sixth or seventh place as expected.

"But at least I was running with them, you could see them and even touch them. This is the way to go and I'm left with a good feeling.

"(Felipe) Massa stopped two laps after me, so it's not like he had a lot more fuel, so yesterday's qualifying was pretty realistic. It's a shame to break down, but I'm left with a great feeling."