Pastor Maldonado became the first non-Ferrari powered driver to top the test times in 2015 on an eventful opening day in Barcelona
The Venezuelan recovered from having caused two red flags early in the day and posted a 1:25.011 in the Lotus E23 on a set of soft compound tyres.
And that final fact is key as the former Spanish Grand Prix winner was only a tenth of a second clear of Kimi Raikkonen in the Ferrari whose 1:25.167 on the medium compound was quicker than Lewis Hamilton's pole position time at the same circuit on the same tyres last year, the Finn also managed 74 laps in the SF15-T.
Mercedes hit by illness
Speaking of the world champion Hamilton he had to conclude his day after just 11 laps in the Mercedes through illness. That meant reserve driver Pascal Wehrlein, driving for Force India in the morning, stepped into the W06 for the afternoon and completed another 48 laps.
Usually Nico Rosberg would have been the man to step in to replace the unwell Hamilton, however, it emerged the German too is suffering from a minor problem as an inflamed nerve in his neck means he would not have been able to cope with the G-forces through the long corners in Barcelona.
Whether either of the race drivers can take to the track on Friday we will have to wait until tomorrow to find out.
McLaren-Honda continue to struggle
Also struggling on day one were McLaren, who missed out on the afternoon as a faulty seal on the electric part of the Honda power unit. It means an engine change is required and as a result they may not be back on track fully until Saturday.
Before the problem there was again signs of progress, however, as Jenson Button completed 21 laps at a competitive pace with a best of 1:28.182.
Susie Wolff impresses for Williams
Making the headlines for much of the day was Williams reserve driver Susie Wolff as the Scot got her first taste of the new FW37.
Wolff completed a series of long runs at a pace very comparable to those seen during last year's race in Catalonia but was involved in a rare testing crash with Sauber's Felipe Nasr with the Brazilian seeming to misjudge where she was approaching turn five and sent both into the gravel trap, hitting the barrier in the case of Nasr.
A stellar effort by the team saw Wolff re-emerge in the final 20 minutes of the day and the former DTM driver completed the day with a second best tally of 86 laps albeit the slowest among those to set a representative time but as mentioned a concentration on long runs was the reason for this.
Teen rookie tops the lap charts
Interestingly, the highest lap tally went to Max Verstappen in the Toro Rosso who enjoyed a quiet but consistent day as the 17-year-old continues to adjust to F1 machinery.
The Dutchman managed 94 laps in total with the sixth best time of 1:27.900 as nobody reached the century mark on Thursday.
Red Bull still lagging
As Ferrari continued to show good pace not just over a single lap but also a very quick long run from Raikkonen, which saw him symbolically overtake a Mercedes out on track on a similar programme, the team most expect their perceived progress will see them fighting against has another solid if not spectacular day.
Red Bull claimed this test would see the beginning of their pre-season after a difficult time at Jerez but it seemed aerodynamic development was the aim of the day on Thursday.
Daniel Ricciardo completed a number of short runs in the morning without completing a time until he finally moved near the top of the standings just before lunchtime. Another series of short runs in the afternoon on the soft compound tyres resulted in the third best time overall with a 1:25.547 but 59 laps perhaps isn't as high as some were hoping to see from the RB11.
Force India make 2015 debut
Force India made their first appearance of 2015 as Sergio Perez took over from Wehrlein in the afternoon.
Using the 2014 car the team managed 66 laps with the Mexican managing two more laps than the German had in the morning and setting the fourth best time of 1:26.636.
Ferrari flattering to deceive?
The main story of the day in terms of how the 2015 grid could look is that lap time from Kimi Raikkonen that was quicker than the Mercedes pole time from last year, given it was two seconds faster than what the Finn himself managed in qualifying in 2014 it shows that clearly Ferrari have made a lot of progress from where they were just nine months ago.
The thing is, however, much of that progress may have been made as the season progressed last year when they were still a long way off the pace set by Mercedes who could have also likely gone much quicker than Hamilton's pole time at the end of the year, therefore just whether Ferrari can be a major threat to those at the front remains something we will only find out in Australia.