Lotus' Pastor Maldonado was fastest on the first day of the second Formula One pre-season test in Barcelona on Thursday as Lewis Hamilton was sidelined for the majority of the day by a fever.
Venezuelan Maldonado's time of 1min 25.011sec was faster than the lap which sealed Hamilton pole position on the same circuit at the Spanish Grand Prix last year.
Ferrari's positive early season vibes also continued as Kimi Raikkonen was second fastest with Red Bull's Daniel Ricciardo in third.
It wasn't such a productive day in the Catalan capital for Mercedes as world champion Hamilton had to pull out due to ill health after completing just 11 laps.
The Englishman was replaced by Mercedes test driver Pascal Wehrlein, who had started the day testing Force India's car from the 2014 season.
"I was quite surprised in the morning when I got the information that I would be driving the Mercedes in the afternoon," said the 20-year-old German.
"But I am here and I want to drive, so I am ready for any opportunity. To drive two Formula One cars in one day was amazing."
Mercedes logged over 500 laps over four days in the first test of the season in the southern Spanish city of Jerez.
Team principal Paddy Lowe explained they hadn't called Nico Rosberg so as to not overtax the German's workload, with last season's runner-up in the world championship due to drive on Friday.
However, reports in the German press claimed Rosberg was also struggling with a neck problem.
McLaren's embryonic relationship with their new engine manufacturer Honda continued to pose problems as a faulty seal requiring a power unit change ended their running for the day after just 21 laps by Jenson Button.
That took the Woking-based team's tally of laps up to just 100 over the first five days of testing after a troubled time in Jerez, and there is every chance that the home fans who turn out to see Fernando Alonso take the wheel on Friday could also be left disappointed.
"We'll need to run a re-designed component to avoid a potential repeat of the problem. Unfortunately, we won't be in possession of that updated part until Saturday, which means that we may face the same problem when we run again tomorrow," said Honda's chief officer of motorsport Yasuhisa Arai.
Elsewhere, Susie Wolff had an eventful day for Williams as she logged more laps than any other driver before lunch and was then involved in a collision with Sauber's Felipe Nasr.
Both drivers were unhurt, but were limited in their running in the afternoon as precious time was wasted in repairing the cars.
"Really unfortunate, the thing you don't want in a test is losing time and unfortunately in the afternoon that happened completely unnecessarily," said Wolff.
"I think it is on video for everyone to see. For me, the facts are I stayed online and he came across and his rear hit my front."
Results from day one of the second pre-season test in Barcelona:
1. Pastor Maldonado (VEN/Lotus) 1:25.011 (69 laps)
2. Kimi Raikkonen (FIN/Ferrari) 1:25.167 (74 laps)
3. Daniel Ricciardo (AUS/Red Bull) 1:25.547 (59 laps)
4. Sergio Perez (MEX/Force India) 1:26.636 (34 laps)
5. Felipe Nasr (BRA/Sauber) 1:27.307 (79 laps)
6. Max Verstappen (NED/Toro Rosso) 1:27.900 (94 laps)
7. Jenson Button (GBR/McLaren-Honda) 1:28.182 (21 laps)
8. Pascal Wehrlein (GER/Force India) 1:28.329 (32 laps)
9. Pascal Wehrlein (GER/Mercedes) 1:28.489 (48 laps)
10. Susie Wolff (GBR/Williams) 1:28.906 (86 laps)
11. Lewis Hamilton (GBR/Mercedes) 1:30.429 (11 laps)
Source: AFP