Mercedes boss Toto Wolff is being cautiously optimistic over the Silver Arrows' chances ahead of the 2018 curtain-raiser in Australia.
Throughout testing the W09 appeared to run consistently around the Barcelona-Catalunya circuit without any mechanical issues.
The Brackley-based outfit also managed to complete the most mileage in pre-season testing racking up nearly 5000km between Lewis Hamilton and Valtteri Bottas, over 500km more than Ferrari.
"Both our drivers seem reasonably happy with our new car, but it remains yet to be seen how well it performs when driven in anger." said the Austrian.
"The reduction in the number of power unit components means that reliability will again play an important role in 2018.
"Our reliability in testing looked good but we need to be careful to draw any conclusions from that – despite getting some good mileage with the new car in Barcelona, many of its components have not even come close to the life they need to complete during the season."
After 2017 witnessed Ferrari take the challenge to Mercedes for the first time in the turbo-hybrid era, early indications from testing now appear to potentially put Red Bull also in the mix with Ferrari and Mercedes.
Wolff claims he isn't taking former success for granted and believes his team are prepared for the potential tussle at the front of the field after months of hard work over the winter break.
"This year promises to bring an exciting three-way fight between us, Ferrari and Red Bull," Wolff added.
"Everyone in Brackley and Brixworth has worked extremely hard over the past months to make sure we enter that fight with the best machine possible."
"Right now, we start this long season on zero points like every one of our rivals. And we have to give it everything to be successful again this year."
