Bruno Senna has been left with work to do in his bid to overhaul points leader Giorgio Pantano following a disappointing GP2 weekend on the streets of Valencia.

Senna had looked set to steal valuable points from his Italian rival in the feature race when Pantano suddenly slowed on the final lap, with his Racing Engineering car running dry and costing the former Jordan F1 man what would have been a dominant win.

However, just as Senna went to pass the stricken car, he too started to slow with a similar problem and although he managed to crawl across the line, it was outside the points in ninth place.

Eager to make amends in the sprint race, Senna made up three places off the line and then took fifth when Pastor Maldonado understeered off into the tyre wall at turn two. Having closed in on Andy Soucek, Senna moved into fourth but not for long as he suffered a spin into the barriers and was forced into retirement.

"I made a good start and the car was running really well," he said. "It isn't easy to pass here and you have to be patient – a tactic that seemed to be paying off. When Andy slowed suddenly I had to slide over the outside kerb to miss him. I rejoined the track cleanly, though, and didn't do any damage.

"It's possible that I got some dirt on my tyres, however, because three corners later the car simply got away from me. I had been sliding through that part of the circuit every lap, but this time it simply went too far. It was just one of those things.

"This weekend has left us with a lot of work to do, but I know we'll be competitive at Spa and Monza. There are four races still to go and this championship is definitely still winnable."

Senna now lies 13 points behind Pantano – who finished third – heading to the penultimate meeting of the year at Spa.