Nico Rosberg set the quickest time in a stop/start final practice session at the Canadian Grand Prix that saw two red flags - one for a bizarre accident involving Felipe Nasr and Montreal's unforgiving walls.
The second red flag, in the final five minutes, was thrown to allow the marshals to recover Jenson Button's stricken McLaren after it stopped on track with an ERS failure. The need to replace part of the power unit means McLaren will not have his car ready for qualifying and he will start the race from the pit lane.
The late red flag also meant several drivers failed to set representative lap times as the track was not reopened before the end of the FP3 hour. Lewis Hamilton, for example, completed just nine laps and finished the session at the bottom of the timesheets after the two red flags interrupted both his soft- and super-soft-tyre runs. Hamilton's one chance at a quick lap on super-softs was lost when he missed his braking point for Turn 1 and continued into the run off. In theory he still had time on the clock to recover for another lap, but Button's stoppage meant he was forced to return to the pits.
As a result, Kimi Raikkonen was second fastest, 0.573s off Hamilton, while Romain Grosjean continued his impressive form this weekend with the third fastest time. Once again Mercedes-powered cars peppered the top ten, with Williams, Lotus and Force India all looking competitive on the long straights of the Circuit Gilles Villeneuve. Daniil Kvyat was sixth fastest in the Red Bull - the highest placed Renault-powered car - ahead of Felipe Massa, who messed up the final chicane ahead of his flying lap on super-soft tyres. Sebastian Vettel will also be looking to improve in qualifying after he only managed eighth.
Nasr's accident came 40 minutes into the session when he lost control of his Sauber and hit the wall after trying to warm his tyres on the back straight. The incident will be classed as a rookie error in an otherwise impressive first season so far, but presents Sauber with a lengthily and expensive repair job on the front of the car ahead of qualifying.
The red flags also worked against Fernando Alonso, who needed a Honda engine change ahead of FP3 and only emerged from the garage in the final ten minutes. Unlike Button, he is expected to take part in qualifying for McLaren, but faces an uphill struggle with just three laps of data gathering and track experience in final practice.