Another busy morning in Barcelona came to an early end thanks to a red flag.

However, for once it wasn't a Haas, Manor or Lotus, rather the world champion's ultra-reliable Mercedes W07.

Twelve minutes before the lunch break, the Mercedes passed the pits, signalling its forthcoming demise with a series of strange noises. Sure enough, at T1 Hamilton pulled to the side of the track bringing out the first red flag of the day.

Mercedes subsequently revealed the cause to be a "transmission problem", thus preventing speculation that Bernie Ecclestone's software experts might have had a hand in things following the world champion's disparaging comments about the sport yesterday.

Sebastian Vettel topped the timesheets, having begun the morning trying the Halo device and then working his way through every conceivable tyre option, posting his best time on the supersoft.

Carlos Sainz was second quickest, the Spaniard posting his best time on the ultrasofts, even though they are not really suited to this track.

Sergio Perez claimed third on the supersofts, having begun his day on full wets, whilst Hamilton's best time, which was good enough for fourth, was posted with the mediums.

A good solid morning for Ricciardo, whilst Button, who posted his best time on ultras, tried some of the updates that arrived yesterday, including a new wing.

Poor Jolyon Palmer will be wondering what he has done to anger the gods, the Briton once again losing track time, whilst Kevin Magnussen never appears to have any issues.

An altogether better morning for Haas, with Romain Grosjean suffering none of the issues that have blighted the team over the previous three days, including yesterday's brake-by-wire problem.

Marcus Ericsson and Felipe Massa had fairly uneventful mornings, whilst Manor, which began the day revealing there was an issue but hoped to be out before lunch, actually got Rio Haryanto out for a sly lap once Hamilton's stricken Mercedes was back in the pitlane.

With temperatures rising, and just four hours of running before they all head down under, we should be in for an eventful afternoon.

Today's Times - All Times Unofficial

Name	Team	Tyres	Laps	Time	Gap
Vettel	Ferrari	SS	54	1:22.852	125.682 mph
Sainz	Toro Rosso	US	57	1:23.134	0.282
Perez	Force India	SS	44	1:23.721	0.869
Hamilton	Mercedes	M	69	1:24.133	1.281
Ricciardo	Red Bull	S	61	1:24.427	1.575
Button	McLaren	US	53	1:24.714	1.862
Ericsson	Sauber	S	57	1:25.031	2.179
Palmer	Renault	S	27	1:25.231	2.379
Grosjean	Haas	S	50	1:25.255	2.403
Massa	Williams	M	63	1:25.696	2.844
Haryanto	Manor		0	No Time