Formula One roared out of its winter hibernation at the first pre-season test in Barcelona this week.

Here, Press Association Sport takes a look at some of the winners and losers following the opening blows of the new campaign.

Winners

Ferrari

The Italian team will leave the four-day test with a skip in their step after appearing to have delivered the best package. Sebastian Vettel and new team-mate Charles Leclerc topped the time sheets on the first two days, and both Mercedes and Red Bull believe the red cars are now the ones to beat. This is just the response Ferrari needed after missing out on both championships last season.

Red Bull

This week could have been a disaster for Red Bull as they grow familiar with new engine supplier, Honda. But the Japanese power unit, which kept conking out in the back of a McLaren, has so far proved reliable for Red Bull. Max Verstappen has looked speedy, too, to suggest the former world champions should be in the mix this season.

McLaren

While it doesn't look as though McLaren, Britain's most successful team, will be battling at the sharp end of the grid, they will take some comfort from an opening test that was not plagued with issues. Last year, McLaren endured a miserable pre-season with a car that was slow and unreliable. But, this term they have delivered a machine that is not breaking down and has racked up credible mileage.

Losers

Mercedes

We have become accustomed to seeing a Mercedes car set the fastest times in opening testing, but, on the evidence at show in Barcelona this week, the Silver Arrows are playing catch-up. Lewis Hamilton has already claimed this will be the most challenging campaign of his seven-season Mercedes career, while team-mate Valtteri Bottas admitted Ferrari hold the edge. It has not been a disaster for Mercedes, not by any stretch of the imagination, but given their recent impeccable standards, there will be cause for concern.

Williams

Deputy team principal Claire Williams spoke of ushering in a new era at the team's Oxfordshire HQ last week only to encounter their worst-ever start to a pre-season campaign. Their car was not ready for the first two-and-a-half days of running, leaving the British team severely on the back foot. Williams described the affair as "embarrassing", and technical chief, Paddy Lowe, now faces a fight to avoid the sack.

Haas

The team's new title sponsor, Rich Energy, said Haas would beat fizzy drinks rivals Red Bull, on and off the track this season. But, perhaps unsurprisingly, Haas do not yet have the speed or reliability to match the front-running team.