Davide Valsecchi played a cagey final feature race of the 2012 GP2 Series season to ensure that he crossed the finish line just ahead of title rival Luiz Razia to confirm that he is this year's drivers champion.

In a race dominated by two safety cars - one at the very beginning, and one near the end - Valsecchi and Razia finished off the podium in fourth and fifth positions, with Max Chilton claiming the race win ahead of Esteban Guti?rrez and Fabio Leimer after a dreadful start for polesitter Luca Filippi.

Filippi looked on the verge of stalling as the lights went out at the start of the Saturday afternoon feature race and he was lucky to get away at all as cars streamed around either side of him, the Coloni car finally slotting into seventh place.

That had gifted Carlin's Max Chilton an easy run down to the first corner in front, and he easily parried some early exploratory lunges from the Lotus of Guti?rrez over the first lap to assert his control of the race. Jolyon Palmer got around Fabio Leimer for third place, while Davide Valsecchi was just where he needed to be to clinch the title - fifth place, three spots ahead of Luiz Razia.

Behind them, there were the usual incidents and collisions going on that were only to be expected in a closed-up pack on a tight and twisty street circuit: Johnny Cecotto Jr. banged wheels with Luca Filippi to gain a place on the first lap; James Calado made light contact with the left rear of Razia's car and almost spun the Arden as the two struggled for position over the opening corners; and Caterham's Rodolfo Gonzalez was involved in two incidents in quick succession, the first leaving Ocean's Victor Guerin in the wall at turn 5 and the second of which saw him tap the Rapax of Ricardo Teixeira into a spin. To rub salt into that latter wound, Gonzalez then ended up running over Teixeira's front wing, and he was rewarded for his efforts with a drive-thru penalty by the race stewards.

The final straw was Ren? Binder spinning and stalling his Venezuela GP Lazarus, which was just one incident too many for the stewards to feel comfortable with and so they they activated a brief safety car to give themselves a chance to clear everything up. Racing soon resumed on lap 3, with Chilton getting an excellent restart and not giving Guti?rrez any chance of taking advantage of the situation: the Carlin driver quickly pulled out nearly a second over the Lotus.

The safety car had been too early for the mandatory pit stop window which didn't open until lap 6: there were early takers in the form of Cecotto, Filippi, Calado and Julian Leal, all of them clearly hoping that the early advantage of fresh rubber would allow them to make up some track position. At the conclusion of his stop, Cecotto was released almost right into the side of Filippi in an apparent text book definition of unsafe release, but Cecotto's quick reactions averted actual contact.

The opening of the pit window coincided with Simon Trummer coming to a rather more unexpected halt out on track when he out-braked himself at the entrance to the tunnel under the main grandstand and stuffed the nose of the Arden into the barrier. That immediately raised the prospect of a second safety car, and a new group of drivers that included Valsecchi, Razia, Leimer, Palmer and Sergio Canamasas reacted accordingly and came onto pit road rather than get caught out.

In fact, Trummer's accident was dealt with under local waved yellows after all without recourse to a safety car. Even so, race leaders Chilton and Guti?rrez felt the need to respond to the majority and came in on lap 8, which left iSport's Marcus Ericsson in the lead with Nigel Melker, Fabio Onidi and Jake Rosenzweig as the only four cars yet to make their mandatory stops. Chilton resumed in fifth place ahead of Guti?rrez with Filippi having jumped back up to seventh place right behind them courtesy of his very early stop, while Jolyon Palmer was up into eighth ahead of Cecotto and Leimer.

Cecotto did not stay in the hunt for long, however: next lap by, he misjudged his run though the tricky turn 10 chicane and took some serious right-side air over the kerbs which left him running off into the wall, causing him to retire on the spot.

Onidi was the final man to come in for his mandatory pit stop at the end of lap 13, which meant that Chilton and Guti?rrez were back in the lead. By now, they had comprehensively started to drop Filippi off the back, and it was clear that the Coloni was paying badly for his very early two-wheel tyre change compared with the leaders who had pitted much later according to their pre-race plans.

Filippi wasn't the only one struggling: behind him in fourth place, Jolyon Palmer was also showing rapidly increasing signs of tyre degradation and dropping off the pace at a precipitous rate. That helped protect the similarly ailing Filippi from attack during the middle of the race, but once Leimer led Valsecchi and Razia past the iSport they were soon taking chunks out of the gap to the Coloni and it was inevitable that Filippi would start to lose positions at a rate of knots. Once Leimer blasted past him, Filippi even briefly featured in the battle for the 2012 drivers championship as he held up Valsecchi and backed the DAMS car dangerously up into the clutches of Razia for a time.

In a similar position further back was another of the early two-wheel stopped, James Calado, who was clearly much slower that the pack of cars massing behind him led by Caterham's Giedo van der Garde, DAMS' Felipe Nasr and the iSport of Marcus Ericsson. Van der Garde made a number of moves on Calado, appeared to have taken the position, only to get thwarted by some very calm and astute race craft from the British driver. Eventually van der Garde's patience snapped and the two went side-by-side through the final corner of lap 15 banging wheels - which allowed Felipe Nasr to pass them both, and Ericsson follow through in close pursuit.

In the end, the tyre degradation was so bad for Filippi and Calado that both were forced to make additional pit tops for new rubber. Palmer would probably have done likewise if he had not already pulled off the track and retired with a mechanical problem on lap 19; while Calado would also pull over and park on lap 23, feeling too ill to continue after suffering from food poisoning in the build up to the weekend only made worse by the stifling humid conditions on race day. He will confirm later whether he's able to participate in the Sunday sprint race.

Filippi would put his new tyres to good use and made a determined charge through the field to try and make it a final weekend in GP2 for Coloni to remember, but it all went wrong on lap 24, not only for Filippi but also for his team mate Fabio Onidi.

First, Onidi locked up his brakes and ploughed into the back of Jake Rosenzweig's Barwa Addax; and then almost at the same moment, Filippi also locked up and in his case ran into the wall at the entrance to the tunnel under the grandstand. He was able to get back underway, but his front wing subsequently failed when he attempted to take the final corner and he found to his cost that he had no downforce, causing him to sail off into the outside wall and bury the Coloni's nose good and proper into the barrier. The damage was extensive enough to preclude Filippi racing in the Sunday sprint race.

That was enough to force the race stewards to re-deploy the safety car. It had been apparent from early on that with the GP2 cars not able to do much better than two minute laps on the Singapore street circuit, there was never going to be any chance of fitting in a 34-lap race before the one hour timed cut off, and so the safety car ended up pulling off just before the cars took the chequered flag at the end of lap 28 instead.

That suited Chilton just fine, as he claimed his second feature race win of the year and his fourth podium of 2012. While deprived of the chance to make a late attack for the win, Guti?rrez was likely also pleased as he never seemed to have the speed necessary to seriously challenge the Carlin for the outright win and was probably relieved not to have to fight off third-placed man Fabio Leimer in the closing laps.

But most significantly of all, Davide Valsecchi had clinched fourth place: and the finish one place ahead of Luiz Razia meant that Valsecchi now had a 27pt lead over the Brazilian in the championship. With only 18pts on offer in the Sunday sprint race, it meant that the matter was decided: Valecchi was confirmed as the 2012 GP2 Series drivers champion, following in the tracks of 2011 champion Romain Grosjean, his predecessor in the DAMS car.

However, that doesn't mean that the year is entirely resolved in terms of titles: Guti?rrez' second place two spots ahead of Valsecchi means that in the team championship battle, Lotus GP had halved DAMS' lead to just 2pts - leaving everything to play for on that front at least on Sunday morning.

[Update: Johnny Cecotto was penalised 3 grid places for Sunday's sprint race after being judged to have crossed the white line at the pit exit during the feature event. Coloni's Fabio Onidi will take a five place penalty on the grid for crashing into the rear of Cecotto's Barwa Addax team mate Jake Rosenzweig. Neither driver finished the feature race and so the penalties do not affect the race final classifications.]

Full feature race results available.