Johnny Cecotto took a surprise first career GP2 pole position in qualifying for the Monaco feature race.
The Addax driver had never previously qualified higher than fifth and is yet to finish on the podium in over two seasons of GP2. But he proved his fastest time in morning practice was no fluke as he blasted to a 1m21.195s lap at the end of the second part of the split qualifying session.
Carlin's Max Chilton was fastest in the first group and will share the front row with Cecotto.
Caterham driver Giedo van der Garde had looked set to top group one as he dominated much of the session with a series of ever-faster laps. But his eventual 1m21.475s proved insufficient when Chilton came through with a 1m21.320s right at the end.
Chilton appeared secure in pole for a spell as the early group two times were some way off his benchmark. Then iSport's Marcus Ericsson produced a 1m21.249s lap to not only blitz his group two rivals, but depose Chilton from outright pole.
Red flags flew soon afterward when Rodolfo Gonzalez (Caterham) crashed at the Swimming Pool entrance. There were just over two minutes left on the clocks at the restart, and that proved to be sufficient time for Cecotto to beat Ericsson by 0.149sec, pushing the Swede back to third.
Ericsson will share row two with van der Garde, while title contenders Luiz Razia (Arden) and Davide Valsecchi (DAMS) line up fifth and seventh, split by Ericsson's teammate Jolyon Palmer.