Ericsson jumps above Sainz into fourth, lowering his time further to a 1:26.080.
A very, very busy day but still no sign of McLaren, Williams or Lotus. We are expecting McLaren shortly....
Ericsson getting quicker and quicker, moving to third with a 1:25.729.
@rockedin123: Thanks! Laurence and I are splitting commentary duty for you today and every day of testing from both Jerez and Barcelona.
Alonso is out on track in the MP4-30 McLaren-Honda. Pictures to follow.
@MichaelDuncan: Absolutely. Remember, this is only the first test of the winter and they will be learning and evaluating everything they brought to Jerez. From that, they will make decisions on improvements to make ahead of the Barcelona tests - but that's the same for every team.
There's your first glance at the 2015 McLaren.
Alonso returns to the pits after one exploratory installation lap. Expect to see more from them later.
As our tweet said, the McLaren sounded very spluttery during that installation lap. Spent much of the first sector coasting around the circuit.
@JohnJenifer: Hard to beat the Red Bull RB11. Shame it's only a livery for pre-season....
I've just returned from the pit lane after watching the first lap for the new McLaren-Honda. Positive to see it get out on track this morning, but it sounded rather rough as it went up the hill from the pit lane exit to Turn One. At one point it sounded like it might cut out altogether, but Alonso completed a full lap and retuned to the pits to the delight of the crowds in the main grandstand. The car looks good, but clearly there will be teething problems getting the power unit running perfectly straight away.
Ricciardo's Red Bull just left a trail of smoke around the first half of the lap but it appears as though it made it back to the pits.
As an update so far, we've seen six cars on track. The Mercedes looks quick and reliable out of the box (as you would expect), the Red Bull also looks promising (a big step up from last year) and is running a funky new testing livery. Ferrari has been out for a few early laps but it's very early days with Vettel behind the wheel for the first time. Sauber have made a very solid start considering rivals Force India aren't here and we are not sure yet if Lotus has its 2015 car in Jerez. Toro Rosso have also got some early mileage under their belts. McLaren has completed two laps now as it gets used to its new Honda power unit.
No sign of Williams we should add, despite rolling the car out in front of the media ahead of the start of the session this morning.
@Keith: Alonso has only been out for three installation laps. In Abu Dhabi last year McLaren registered just five laps in two days with the new Honda power unit, so the car is running a little bit more smoothly today. They will build up to longer runs later today as long as these early laps go well.
@MichaelDuncan: We should also remember that this is the first morning of testing. A lot will change on the cars over the tests and again for the first race in Melbourne. However, it would be a massive surprise if Mercedes weren't the team to beat this year.
Rosberg is still fastest and has the most laps. But a lot of today is about system checks and getting everything on the car working together. Not an easy task considering many of these cars were only finished in the last week or two.
Alonso has gone out today in the McLaren again. It's likely to be another exploratory lap before returning to the pits.
Alonso stays out for a second lap this time. That's progress at least!
Meanwhile, at Williams....
@MichaelDuncan: I think you're right. Renault and Ferrari spent much of last year getting the power unit up and running reliably, but it was another thing to optimise the ERS and fuel efficiency. In theory they had more to gain over the winter just from getting the more potential from what they already had, plus the updates over the winter. However, Mercedes won't be standing still.
Alonso returns to the pits after setting an initial time of 1:40.738 on a three lap run. Six laps in total now.
Bottas has now left the pits in the WIlliams, so we've now had all the cars that are here on track. The new Lotus is making its way over from the UK today.
@MichaelDuncan: So much of the aerodynamics is based on the power unit and its packaging and cooling requirements. However, I suspect Red Bull will make big strides as it works one-on-one with Renault. Mercedes, of course, already have that advantage.