A last-gasp flying lap from Johnny Cecotto on super soft tyres gave the Addax driver first place at the end of GP2 free practice in Monte Carlo.
Cecotto and championship leader Davide Valsecchi jumped to first and second just after yellow flags for an incident involving Cecotto's team-mate Josef Kral were removed.
Although a massive 0.670 seconds separated Cecotto's 1m22.075s benchmark from Valsecchi's second-placed time, the DAMS driver was using soft tyres rather than super softs like his rival.
Racing Engineering's Fabio Leimer had looked set to stay on top with his 1m22.750s as the yellow flags flew in the final minute, before swift work by the marshals allowed Cecotto and Valsecchi to stay on the accelerator on their last laps and demote Leimer to third.
Giedo van der Garde had led the way for Caterham for much of the session, but spun and tapped the barriers at Rascasse with four minutes to go, ending his morning. The Dutchman was then pushed back to fourth.
Jolyon Palmer (iSport) and early pacesetter Luiz Razia (Arden) completed the top six, ahead of Coloni's Stefano Coletti, Carlin's Max Chilton (who also held first for a spell), Leimer's team-mate Nathanael Berthon, and Kral.
The latter's incident came when he spun out of the second part of the Swimming Pool and brushed the barriers.
Also in trouble were Lazarus man Giancarlo Serenelli, who spun and stalled at Rascasse, and Lotus's Esteban Gutierrez, who crashed at Sainte Devote before he could set a representative time.
Pos Driver Team Time Gap 1. Johnny Cecotto Addax 1m22.075s 2. Davide Valsecchi DAMS 1m22.745s + 0.670s 3. Fabio Leimer Racing Engineering 1m22.750s + 0.675s 4. Giedo van der Garde Caterham 1m22.757s + 0.682s 5. Jolyon Palmer iSport 1m22.842s + 0.767s 6. Luiz Razia Arden 1m23.104s + 1.029s 7. Stefano Coletti Coloni 1m23.343s + 1.268s 8. Max Chilton Carlin 1m23.429s + 1.354s 9. Nathanael Berthon Racing Engineering 1m23.445s + 1.370s 10. Josef Kral Addax 1m23.463s + 1.388s 11. Tom Dillmann Rapax 1m23.626s + 1.551s 12. Marcus Ericsson iSport 1m24.009s + 1.934s 13. James Calado Lotus 1m24.062s + 1.987s 14. Nigel Melker Ocean 1m24.125s + 2.050s 15. Felipe Nasr DAMS 1m24.154s + 2.079s 16. Fabio Onidi Coloni 1m24.160s + 2.085s 17. Stephane Richelmi Trident 1m24.268s + 2.193s 18. Julian Leal Trident 1m24.315s + 2.240s 19. Rodolfo Gonzalez Caterham 1m24.400s + 2.325s 20. Simon Trummer Arden 1m24.629s + 2.554s 21. Victor Guerin Ocean 1m24.868s + 2.793s 22. Rio Haryanto Carlin 1m25.748s + 3.673s 23. Fabrizio Crestani Lazarus 1m25.827s + 3.752s 24. Ricardo Teixeira Rapax 1m26.680s + 4.605s 25. Giancarlo Serenelli Lazarus 1m29.407s + 7.332s 26. Esteban Gutierrez Lotus 1m36.944s + 14.869s