Ferrari fans have been given cause for concern ahead of the new Formula One season after a day to forget in testing.
Champions Mercedes ended F1's first pre-season test with comfortably the quickest lap time in Barcelona on Friday.
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However, it was an engine failure and lack of pace for Ferrari that left team bosses particularly concerned.
Ferrari dominated testing last year before seeing Mercedes make a mockery of that early pace by running away with the championship.
This year, they are already behind the eight-ball after seeing Sebastian Vettel break down early on the third and final day of testing at the Circuit de Catalunya.
Vettel was 12th fastest overall after suffering the engine failure midway through the morning session.
The SF1000 was loaded onto the back of a truck and transported back to pit lane, where it remained under a blanket.
Ferrari team boss Mattia Binotto admitted that his team has plenty to figure out before next week's final three-day testing exercise.
"I am not as optimistic as last year so it means the others are faster than us at the moment,” Binotto said.
"How much faster it's really difficult to judge. We will go through all the data."
After winning just three of 21 races last year, Ferrari's focus was on improving the aerodynamics of the SF1000.
Binotto said despite their setback in testing, it's “a very early stage to decide” whether Ferrari has made up ground on their rivals for 2020.
"I've seen certainly Mercedes, and Red Bull, very fast in these first days. But I think we will assess the true performance only next week or in Australia,” he said.
“That will be true performance to start the season with, knowing that 22 races are very long and everything may change.
"We changed the approach to testing so we focused the first sessions on trying to map the car in various aero and mechanical configurations without really trying to optimise the set-up and look for overall performance.
"On the other side it is true that last year at this stage I was more optimistic because the lap time was easier to find… while if it is true we did not focus on set-up work or performance, it seems it is more difficult.
“The competitors apparently are very strong but we should not forget the story of last year and let's wait until next week and Australia to better understand the true picture."
Mercedes lead the way in testing
Valtteri Bottas, whose teammate Lewis Hamilton is aiming to equal Michael Schumacher's record seven titles, led the way with a lap of the Circuit de Catalunya only just slower than the all-time track record.
The Finn's time of one minute 1:15.732 in the morning compared to the record of 1:15.406 he set in qualifying for last year's Spanish Grand Prix.
Bottas had also completed 65 laps, one short of a full race distance, by lunchtime when Hamilton took over for another 73 laps and with the day's second best time of 1:16.516.
Renault's Esteban Ocon was best of the rest, 1.370 slower but with 76 laps on the board.
Ocon's Australian teammate Daniel Ricciardo was seventh fastest after chalking up 93 laps which left Renault executive team boss Marcin Budkowski delighted.
"We achieved high mileage with 169 laps in total and tried the softer compounds ahead of the second test next week," he said.
"Importantly both drivers are happy, the car has a good balance and is performing well and we're pleased with the progress we've made this week."
Max Verstappen, who did 168 laps on Wednesday, again pounded out more than any other driver in the morning with a total of 86.
Alfa Romeo's Antonio Giovinazzi was the big lapper of the day, with 152 for Alfa Romeo.
The final three-day test kicks off back in Barcelona on Wednesday, before Hamilton opens his championship defence in Australia on March 15.