Lewis Hamilton topped an eventful opening practice session for the Monaco Grand Prix which was stopped prematurely after a loose manhole cover was kicked up onto the circuit.
The session came to a conclusion three minutes early when Nico Rosberg's Mercedes appeared to kick up a manhole cover at the bottom of the hill at Turn 1, which bounced across the track and underneath the McLaren of Jenson Button. The cover destroyed the McLaren's front wing and gave the 2009 world champion a puncture, an incident which could have been much more serious if the cover had bounced towards the cockpit area. After an inspection by FIA race director Charlie Whiting, a replacement manhole cover was welded back into place to avoid a repeat in afternoon F1, GP2 and Porsche Supercup sessions.
Nasty moment for Jenson when he hit the drain cover dislodged by Nico R at Ste Devote pic.twitter.com/u8TZlQs6Bc
— Peter Windsor (@PeterDWindsor) May 26, 2016
Rosberg finished the morning one tenth behind Hamilton, who topped the first session since the pair's coming together on the opening lap of the Spanish Grand Prix. The Mercedes drivers completed their first laps on the ultra-soft tyre, which they did not use during winter testing, and look to have retained a significant one-lap advantage.
There were several offs during the session, with Felipe Massa putting his Williams in the wall at Ste Devote and damaging the left side of his car. The Brazilian driver did not emerge again but was not the only man to be caught out by the first corner, with several drivers including Hamilton locking up and running into the deep run-off area later in the session. In the final half hour Jolyon Palmer hit the wall after getting some oversteer at Tabac, costing the Englishman valuable track time at the end of the session.
Away from the session-leading Mercedes, Ferrari's Sebastian Vettel was the nearest competitor four tenths behind. The German driver had a three tenths advantage over Red Bull drivers Daniel Ricciardo and Max Verstappen, with Toro Rosso's Daniil Kvyat claiming an impressive spot in the top six. Force India pair Nico Hulkenberg and Sergio Perez finished ahead of Kimi Raikkonen, who appeared to lock up heavily on his flying ultra-soft lap, finishing 1.3s off the pace of Hamilton.
Carlos Sainz finished tenth, ahead of Valtteri Bottas and Romain Grosjean. McLaren hopes for a competitive weekend in Monte Carlo but started the weekend with Fernando Alonso in 13th and Jenson Button in 15th though opening practice is rarely a good indication of pace. The McLaren drivers finished either side of Esteban Gutierrez, who stopped on track in the final hour at Portier.
Sauber drivers Felipe Nasr and Marcus Ericsson finished either side of Renault driver Kevin Magnussen in 17th, with Felipe Massa having to settle for 19th after his session was restricted to just 10 laps. Palmer's late shunt prevented him from improving on 20th, with Manor drivers Rio Haryanto and Pascal Wehrlein rounding off the order at the foot of the timing screens.