Monaco GP: Ferrari gearbox issue caused Kimi Raikkonen's problems

Raikkonen set the sixth fastest time in Thursday morning's dry session, but was classified slowest of the 22 runners, 27 seconds off the pace, after clocking just four laps in the wet/dry second session.

The Finn said a gearbox gremlin had forced him out of the session before he could set a representative time.

"Unfortunately, the bad weather affected this first day of practice and halved the possibility to complete the work we had planned," said Raikkonen.

"In the morning, on the dry track, we tried various set-up options, without encountering any particular problems, apart from a lack of grip at the front under braking.

"In the afternoon, we made a few changes to improve the balance of the car, but having waited almost an hour before being able to go out, a problem with the gearbox prevented me from completing the session.

"On Saturday we will try and make the most of the third free practice session to complete our programme for qualifying, which we know is the key factor here."

Team-mate Alonso outpaced championship leader Lewis Hamilton's Mercedes by just over four tenths of a second to top the session for Ferrari.

The Spaniard said the lack of long running on the super-soft tyre in practice two would pose a challenge for teams come the race.

"The increase in grip we found over the few laps we did with the super-soft tyres leaves us in no doubt that this will be the tyre to use on Saturday afternoon," Alonso said.

"For the race there is still a lot to learn as no one has done a long run, so we might have to improvise when it comes to strategy."