Raikkonen fastest as McLaren hit trouble on day four

Raikkonen’s time of 1m 23.477s was the third quickest of the week so far, and left him a full 1.786s clear of Renault’s Kevin Magnussen, who used the soft tyres to go second fastest and also added a further 67 laps to the 111 he managed on Wednesday.

Toro Rosso's Max Verstappen was third quickest at the lunchbreak as he enjoyed his second run-out in the new STR11, just ahead of stablemate Daniil Kvyat’s Red Bull, Felipe Nasr’s 2015-spec Sauber and Lewis Hamilton’s seemingly bulletproof Mercedes.

In another ominous display, the world champion almost broke into triple figures for laps, clocking 99 tours in an F1 W07 Hybrid fitted with an 's-duct' for the first time. Nico Rosberg will undoubtedly look to match that lap tally when he takes over in the Silver Arrow this afternoon.

Elsewhere, Rio Haryanto had another encouraging morning for Manor, posting the eight quickest time and logging 43 laps, but it was a much quieter session for newcomers Haas, who completed just 26 laps with Esteban Gutierrez at the wheel.

The opening pre-season test of the year concludes this afternoon.

Thursday morning's unofficial testing times from Barcelona