The Williams, driven by Briton George Russell, finally made it on to the track at the Circuit de Barcelona-Catalunya on Wednesday - with a day and a half left of the four-day test and was 13th fastest.

Deputy team principal Claire Williams said: "It's not a situation that we anticipated, or that we ever wanted to find ourselves in."

The 21-year-old Russell was eight seconds off the pace set by Toro Rosso's Daniil Kvyat, who - after a late run on the fastest tyre - pipped Alfa Romeo's Kimi Raikkonen by 0.058 seconds.

Williams added: "We're not just disappointed. It's embarrassing not bringing a race car to a circuit when everyone else has managed to do that, particularly a team like ours that has managed to bring a race car to testing for the past 40-odd years."

Image source, Getty Images

Charles Leclerc put Ferrari on top for the second day in a row at the start of pre-season testing in Spain. The 21-year-old Monegasque, who steps up to Ferrari this season after an impressive debut year in 2018, headed McLaren's British novice Lando Norris.

Leclerc's time was within 0.1 seconds of that achieved by team-mate Sebastian Vettel in setting the pace on Monday. Red Bull's Pierre Gasly had a crash late in the day, while world champion Lewis Hamilton was 10th for Mercedes.

Gasly lost control on the entry to Turn 12 and spun into the gravel trap late in the afternoon, brushing the barrier with his rear wing. The Frenchman looked mortified to have crashed on his first day in a new car following his promotion to a top team, after spending last year with Red Bull junior team Toro Rosso.

Gasly sat in the car for some time after the incident, and when he climbed out left his helmet on until he had returned to the pits and gone out of sight at the back of the garage.

He was not the only driver to have a 'moment' - Leclerc had a spin at the chicane, as Vettel did on Monday, while British-born Thai novice Alexander Albon spun into the gravel on his first lap out of the pits on his debut for Toro Rosso.

Albon later spun again and ended the day fourth quickest of 11 drivers who took part in the day, using the second-fastest C2 tyres, which Norris also used for his quick time late in the day.

Image source, Getty Images

Meanwhile, back in Barcelona, we have lap times from seven of our 10 drivers this morning. Pierre Gasly, looking to show what he can do after his promotion from Toro Rosso to Red Bull, is leading the way.

1. Gasly 1.19.973
2. Magnussen 1.20.358
3. Leclerc 1.20.850
4. Hulkenberg 1.21.728
5. Hamilton 1.23.502
6. Giovinazzi 1.23.912
7. Albon 1.24.392

Ferrari's Sebastian Vettel set the pace, with a lap 0.4 seconds quicker than McLaren's Carlos Sainz, while Williams did not take part in the day, with Haas driver Romain Grosjean third quickest and Red Bull's Max Verstappen fourth.

"We couldn't have hoped for a better day," said Vettel, who completed 169 laps, more than any other driver. "It was unbelievable. The car was working really well, we had no issues slowing us down. We actually completed the programme just the way we wanted. And were able to squeeze a little bit more out even."

Williams deputy team principal Claire Williams described their delay as "extremely disappointing".

Lewis Hamilton, who drove only in the afternoon after taking over from Mercedes team-mate Valtteri Bottas, was ninth fastest as the world champion, as usual, concentrated on longer runs in testing.

Mercedes F1 boss Toto Wolff said Ferrari "looked ultra-strong" but added no team was chasing ultimate lap times.

With not much going on at the moment, time to take a quick look back at last week's action in the first four days of testing.

Chris Medland
F1 journalist in Barcelona

Another cold but clear start kicks off the second week of testing, but it’s hardly an action-packed first 20 minutes. After all 10 cars complete installation laps, Lewis Hamilton enjoys the track all to himself while carrying out aerodynamic data gathering, performing constant-speed runs along the pit straight.

There are a number of Hamilton flags opposite the Mercedes garage in support of the defending champion, while the lack of movement elsewhere means the majority of media are camped outside the team’s pit box.

Image source, Chris Medland

We only have one timed lap so far, and that has come from Lewis Hamilton with a 1:23.502. It will get much quicker.

It may be sunny in Barcelona but six degrees is a chilly start to the action. Still, it is better than this time last year when it was snowing on one of the days.

No-one dared go out for most of that day, before Fernando Alonso gingerly made his way around with about five minutes of the session with a lap time of nearly two and a half minutes.

Williams were late arrivers to the party last week, no delays to this one though with George Russell in action today.

Mercedes, Ferrari and Renault are switching their drivers around later on, meaning Valtteri Bottas, Sebastian Vettel and Daniel Ricciardo all get a chance to show us what they can do this afternoon. For the other seven teams, just the one man out there for them today.

No messing about today. Everyone's had their breakfast and are eager to go. Our early gladiators are...

• Lando Norris (Great Britain) - McLaren
• Nico Hulkenberg (Germany) - Renault
• Antonio Giovinazzi (Italy) - Alfa Romeo
• George Russell (Great Britain) - Williams
• Alexander Albon (Thailand) - Toro Rosso
• Pierre Gasly (France) - Red Bull
• Lance Stroll (Canada) - Racing Point
• Lewis Hamilton (Great Britain) - Mercedes
• Kevin Magnussen (Denmark) - Haas
• Charles Leclerc (Monaco) - Ferrari

Ten teams, one driver from each, no-one missing. A good start to the week.

Good to speak to you again.

As always we want your thoughts and observations on all the action so don't be shy, no hiding and have your say. Tweet us using the hashtag #bbcf1 and we will post your words of wisdom in this page throughout the day.

Hello and welcome to BBC Sport's live text commentary from the opening day of second testing before the opening Formula 1 race next month.

I'm Michael Emons and will be guiding you through the action today. Let's get going...

Mercedes have dominated Formula 1 for the past five years, but early indications are that they might not have it all their own way in 2019.

The general feeling from the first four days of testing was that Ferrari had the edge, but how will Mercedes respond today?

Image source, Getty Images