Davide Valsecchi came through from eighth on the grid to add a stunning GP2 sprint race victory in Bahrain to his Saturday feature win.
The DAMS driver charged up behind leader Esteban Gutierrez - who had only moved to the front when long-time leader Fabio Leimer was penalised - and grabbed first place at the start of the very last lap as Gutierrez struggled for tyre grip.
Valsecchi had not looked a likely winner until the closing stages, initially making quietly stealthy progress up the order as Lotus team-mates James Calado and Gutierrez fought for victory with Racing Engineering's Leimer.
Calado had jumped from fourth on the grid to lead at the start, ahead of Leimer and Gutierrez. The Sauber protege soon passed Leimer and then attacked team-mate Calado, who locked up heavily in defence at Turn 1 on lap three. The pair then made light contact exiting the corner, ripping a chunk of front wing from Gutierrez's car and allowing Leimer to get between them.
Then it was Leimer's turn to hit the front, passing Calado on lap five, with Gutierrez following him through. Leimer subsequently edged away and looked set for victory, only for the stewards to give the Racing Engineering man a drive-through penalty for failing to heed yellow flags, forcing him to relinquish the lead with six laps to go.
By that time, Valsecchi's charge was underway. Already up to third after passing Max Chilton (Carlin) and Calado in quick succession, Valsecchi moved into second following Leimer's penalty, and having conserved his tyres, the Italian was able to swiftly demolish Gutierrez's seemingly comfortable advantage - catching up at a second per lap.
Going into the final lap, Gutierrez firmly defended the inside going into Turn 1, but Valsecchi was able to cut across on the exit of the corner and grab the lead as Gutierrez slithered out of the turn, before inching away to take a superb win and increase his championship lead.
Calado held on for third, ahead of Valsecchi's title rival Luiz Razia (Arden) and Chilton.
Valsecchi's team-mate Felipe Nasr almost eclipsed the winner's heroics, as he surged through from a pitlane start to take an incredible sixth place. iSport's Jolyon Palmer mounted a comparable charge from the back row to seventh amid some epic midfield racing, ahead of Simon Trummer (Arden), Giedo van der Garde (Caterham), and Tom Dillmann - whose Rapax car should have started third but stalled before the formation lap.
Polesitter Fabio Onidi swiftly lost ground after a poor start and could only finish 14th for Coloni, while Leimer's penalty left him 12th.
Results - 22 laps: Pos Driver Team Time/Gap 1. Davide Valsecchi DAMS 39m22.363s 2. Esteban Gutierrez Lotus + 0.399s 3. James Calado Lotus + 10.617s 4. Luiz Razia Arden + 12.463s 5. Max Chilton Carlin + 13.573s 6. Felipe Nasr DAMS + 15.414s 7. Jolyon Palmer iSport + 22.950s 8. Simon Trummer Arden + 30.425s 9. Giedo van der Garde Caterham + 31.976s 10. Tom Dillmann Rapax + 32.545s 11. Dani Clos Addax + 32.632s 12. Fabio Leimer Racing Engineering + 32.856s 13. Ricardo Teixeira Rapax + 36.275s 14. Fabio Onidi Coloni + 36.477s 15. Rio Haryanto Carlin + 39.988s 16. Marcus Ericsson iSport + 40.386s 17. Julian Leal Trident + 47.410s 18. Nigel Melker Ocean + 56.196s 19. Fabrizio Crestani Lazarus + 59.488s 20. Rodolfo Gonzalez Caterham + 1m52.968s 21. Giancarlo Serenelli Lazarus + 1m53.295s 22. Johnny Cecotto Addax + 1 lap 23. Stefano Coletti Coloni + 2 laps Retirements: Nathanael Berthon Racing Engineering 15 laps Brendon Hartley Ocean 2 laps Stephane Richelmi Trident 0 laps