Sam Bird led the way in an eventful Formula Renault 3.5 free practice session around the streets of Monaco.
The Briton, who took pole position in the principality in GP2 last year, had a couple of stints at the top of the times as the session went into its closing stages. On both occasions ISR driver Bird deposed Alexander Rossi from top spot, and the Arden Caterham driver was unable to respond after he crashed at Casino Square toward the end of the session.
A late effort from Marco Sorenson dropped Rossi to third, and the American was far from the only driver to hit trouble as the field tried to make the most of its only track time before qualifying on Saturday morning.
Sorenson's Lotus teammate Richie Stanaway kicked things off with an early crash after striking the curbs at the Swimming Pool, while Lucas Foresti caused the first red flag when he spun at Rascasse and caused a traffic jam.
At the same time his DAMS teammate Arthur Pic went off at St. Devote. The Frenchman had managed to keep his car out of the barriers, but he could not prevent it from stalling as he tried to rejoin the track.
Ferrari junior driver Jules Bianchi was in the wars again when his car developed a small fire with 20 minutes to go, and the Tech 1 driver had to complete a whole lap with a smoking car as it started just as he passed the pit entrance.
Carlos Huertas and Giovanni Venturini also hit trouble in the closing stages, and the session concluded under a red flag with Bird on top.
Despite his crash Rossi ended up third behind Sorenson. Kevin Korjus was fourth for Tech 1, ahead of a trio of rookies in Kevin Magnussen (Carlin), Nico Muller (Draco), and championship leader Robin Frijns (Fortec).
Red Bull-backed Lewis Williamson's tough start to the season continued, as the Scot's track time was halted when his Arden car got stuck in gear.