Lewis Hamilton tops rain-interrupted second practice in Monaco

The Mercedes pair of Hamilton and Nico Rosberg topped the times after 20 minutes of the session, with Hamilton fastest on a 1:17.192. At that point, Roberto Merhi hit the wall exiting the tunnel to bring out a red flag.

Merhi lost control of his Manor under braking for the Nouvelle Chicane, attempting to catch the rear as it stepped out but over-correcting to spear in to the barrier on the outside of the track, breaking the front wing before a second impact also appeared to damage the front right suspension.

The incident brought out the red flag while the car was recovered and the debris cleared, and during that break the rain started to fall. Pastor Maldonado bizarrely attempted a lap on supersoft tyres but found the track too wet and then the rain intensified to confine everyone to their garages.

The heavy rain eventually stopped to allow running on wet or intermediate tyres in the final 15 minutes of the session, with a threat of rain on Sunday making some wet running useful for the teams.

Despite the tricky conditions, the closing stages of the session passed largely without incident, with Daniil Kvyat the only man to go off as he made use of the escape road at Ste Devote having failed to get his Red Bull slowed sufficiently for the first corner.

Due to the rain the times from the first 20 minutes therefore went unbeaten, with Hamilton heading Rosberg by three quarters of a second. Sebastian Vettel was third - 1.1s slower than Hamilton - with team-mate Kimi Raikkonen another 0.2s further back in fourth place.

Kvyat was fifth for Red Bull - 0.005s off Raikkonen's time - ahead of the impressive Toro Rosso pair of Carlos Sainz and Max Verstappen. Fernando Alonso finished the session in the top ten ahead of Nico Hulkenberg and Romain Grosjean.

Aside from Merhi's incident, Marcus Ericsson also hit trouble as the team kept him in the garage throught the session as it investigated what it simply described as a mechanical issue.