Romain Grosjean spins in the pack, triggering a multicar accident. (Image by Zak Mauger/LAT)

Raikkonen was one of six retirements, with three of those coming on the opening lap courtesy of a dangerous crash. Grosjean was up to eighth place behind teammate Kevin Magnussen entering Turn 3, but the lead Haas got a bit out of shape and drifted slightly wide, forcing Grosjean wider and causing him to lose downforce. The Frenchman lost the rear of his car but kept his foot in and lit the rear tires, spinning back across in front of the pack in a cloud of tire smoke.

The following cars all darted in different directions but Nico Hulkenberg and Pierre Gasly were both collected by the Haas as a number of other unsighted drivers were forced to take evasive action.

The incident will be investigated after the race but Grosjean could be in for a retrospective penalty, while the debris and damage required six laps behind the Safety Car before Hamilton could start to pull away.

Kevin Magnussen, Haas F1 Team VF-18 Ferrari, leads Carlos Sainz Jr., Renault Sport F1 Team R.S. 18, Fernando Alonso, McLaren MCL33 Renault and Romain Grosjean, Haas F1 Team VF-18 Ferrari, as Stoffel Vandoorne, McLaren MCL33 Renault, and Marcus Ericsson, Sauber C37 Ferrari, run wide during the Spanish GP at Circuit de Barcelona-Catalunya on May 13, 2018 in Circuit de Barcelona-Catalunya, Spain. (Image by Glenn Dunbar/LAT)

Despite the trouble for one Haas, the other of Magnussen escaped unscathed and enjoyed a clean run to finish sixth after Raikkonen retired, ending up 50 seconds adrift of Ricciardo but over half a minute clear of Carlos Sainz.

On the first restart on Lap 7, the biggest mover was Fernando Alonso as he overtook Ocon around the outside of Turn 3 with an excellent move, moving up to 10th place having lost ground at the start. Alonso was on the supersoft tire but managed to stretch out his opening stint long enough to pit just once, passing Charles Leclerc for eighth place when the VSC ended on lap 42.

Leclerc had shown some excellent defensive driving when running in the top 10 throughout the race but he dropped back in the closing stages, losing out to Sergio Perez with fewer than 10 laps remaining as the Force India used DRS on the run to Turn 1. The Sauber still held on for a point in 10th place, with Stroll less than five seconds adrift in 11th and Brendon Hartley 12th but coasting across the line.

Marcus Ericsson and Sergey Sirotkin were the only other two finishers, with the Russian three-stopping and suffering a strange off-track moment at Turn 12 toward the end of a dismal weekend for Williams.

As well as Ocon, Raikkonen and the trio on the opening lap, Stoffel Vandoorne also retired as he pulled into the pit exit after coasting down the pit straight with a loss of power. Vandoorne also picked up a penalty point as a result of going off track at the start and not following the race director’s instructions to go around a marker when rejoining at Turn 2.

Hamilton’s 64th victory extends his championship lead to 17 points ahead of Vettel, with Bottas now 20 points behind the Ferrari in third.

– Chris Medland