Giorgio Pantano came from fifth on the grid to win a thrilling GP2 Series encounter at Silverstone, strengthening his hold on the lead of the drivers' championship.

The Italian laid down a huge marker to the rest of the field - in particular title rivals Bruno Senna and Romain Grosjean - after exploding past his rivals to steal an incredible victory after hunting down Lucas di Grassi with six laps to run. Despite not running right at the front for the majority of the race, the Racing Engineering driver kept his head while those around him in the leading group were losing theirs, managing his tyres and timing his challenge to perfection.

Senna converted his pole position into an early lead, with di Grassi easily muscling his way past a slow Romain Grosjean into Copse, but, three laps into the race, the iSport car was off the road at Stowe after being pushed in too deep by the gusting wind, undoing all of Senna's good work as his rivals went steaming through.

With Alvaro Parente and Andi Zuber showing just how tricky the track and conditions could be, the order continued to shuffle and, even when back up to speed, Senna had to fight hard just to hold position. di Grassi, meanwhile, continued to extend his lead while those behind fought, and was 3.5secs to the good after a dozen laps.

Grosjean was by then back up to second, having benefited from the slips by Senna and Zuber, with Pantano third ahead of the Brazilian and iSport Karun Chandhok, who was picking up places with regularity. The Frenchman was also the first of the frontrunners to make his mandatory stop, a lap before Pantano and two earlier than di Grassi.

They rejoined in the same order but Senna, who followed di Grassi in on lap 17 was further delayed when his countryman exited across his bows. The iSport car rejoined in tenth, albeit with several non-stoppers clouding the true picture

If the first two-thirds of the race had been entertaining enough, it was nothing compared to the remainder, with Grosjean and Pantano closing on di Grassi, and the iSport team-mates attempting to make their way deeper into the points as they chased down a struggling Zuber.

Once Pantano had disposed of Grosjean in a wheel-banging move at Abbey, the Italian was away in pursuit of di Grassi, leaving his prey to fall back towards the group behind, clearly struggling with his brakes, which locked and gave great clouds of tyre smoke at every opportunity.

With S?bastien Buemi piling on the pressure behind Senna, the battle for third had the potential to be a five-way scrap until Chandhok finally got passed Grosjean at Brooklands. The Indian had earlier pulled off a great switchback move at Stowe, only to find yellow flags for Pastor Maldonado's crashed car that obliged him to let the Frenchman back through. Undaunted, Chandhok maintained the pressure before making his move in the stadium section, and was able to take a comfortable podium thereafter.

Pantano, too, was up a position. Having rapidly closed down the 3.7secs gap that di Grassi had enjoyed before the Italian dispensed with Grosjean, the Racing Engineering car hounded its Campos rival for several laps before replicating Nigel Mansell's famous feint on Nelson Piquet at Stowe to claim the lead. With di Grassi spent in launching an immediate defence, the championship leader remained untroubled to the flag.

The action wasn't done with the podium places being sorted, however, for Grosjean continued to thwart Senna, who had Buemi looking for an opportunity to make up further positions. With Buemi having ducked past Senna at Bridge, and then almost capitalised on Grosjean running wide at Copse with two to go, the trio twice went three-abreast through sections of Becketts.

Senna thought he had regained fifth by passing Buemi at Stowe, only to lose it by running wide at Vale. Buemi then passed Grosjean in the second of their hair-raising duels at Becketts, before Senna banged wheels with the Frenchman at Stowe and claimed the place at Vale. Even then, the drama wasn't over, for the iSport car ran out of road entering Priory for the final time, again undoing all its pilots good work as Grosjean nipped back through and won the drag race to the line.

Almost lost in the excitement ahead of them, Zuber and Luca Filippi rounded out the points, and will start on the front row in Sunday's sprint, while Jerome d'Ambrosio and Vitaly Petrov - who had spent much of his race trying to negotiate a stubborn midfield typified by Javi Villa - completed the top ten.

Kamui Kobayashi could have been a candidate for points, notably for fastest lap, but had his hard work undone by a mechanical gremlin, becoming one of only three retirements, alongside Maldonado and Carlos Iaconelli, the latter failing to even complete the warm-up lap before pulling off at Stowe. Local favourite Mike Conway botched his start and plummeted to the wrong end of the field, eventually coming home a disappointed 14th, while Magny-Cours podium finisher Yelmer Buurman trailed his former F3 rival by a couple of tenths. Davide Valsecchi claimed 19th on his return from injury.

It was Pantano's day, however, the Italian having finally found the Silverstone podium at the seventh attempt, claiming his third win of the year - the only driver with multiple successes in 2008 - and extending his championship lead over Senna to 13 points with the addition of the bonus for fastest lap. He will start eighth on Sunday but, on this form, few would bet against him finding those steps again.