Daniel Ricciardo was optimistic about challenging Mercedes during the upcoming 2018 Formula 1 campaign after Red Bull Racing set the fastest time of winter testing on day two of the second pre-season test Wednesday.

The Australian’s 1:18.047 around the Circuit de Catalunya in the RB14 was that fastest ever time in its current layout, and it was around three and a half tenths quicker than Lewis Hamilton, who was second on the time sheets.

Mercedes will start the season as favorites owing to its domination for the last four years, with only Ferrari getting close to challenging it in 2017. Hamilton had set the fastest time until Wednesday and it came in the final day of the first pre-season test.

Ricciardo has put down the marker ahead of the final two days of testing and it remains to be seen if Mercedes and Ferrari will respond to Red Bull’s challenge as they begin to stretch their cars to the limit in preparation for the opening race of the 2018 season in Melbourne on March 25.

However, the Red Bull driver still believes Mercedes are slightly ahead as his time was set on the fastest tire compound available this season — the hypersoft tire — while the Mercedes duo of Hamilton and Valtteri Bottas, who were second and third on the time sheet set their time on the ultrasoft tire, which is one level below.

“We are getting there,” Ricciardo said, as quoted on Formula 1’s official site. “The Mercs still look pretty quick. I don’t believe that they are on the hypersofts. I think Lewis might have been on the ultra, from what I heard. Maybe [Valtteri] Bottas as well. And I guess their qualifying mode, when they decided to use it, will probably be a bit more than ours as well.”

“I think that they still have a bit more on the rest, but it is not too bad. We are looking pretty good. Not really sure about Ferrari at the moment, but we are in a decent place.

Red Bull Racing Red Bull Racing's RB14 has proved that it has the potential to challenge Mercedes in 2018. Photo: Getty

“We will still work on a few weaknesses but generally it does not feel too bad. Mercedes are still quick, if everything was equal right now they still have a little bit on the rest, but I don’t think it is too big. So it seems positive,” the Australian continued.

Ferrari, on the other hand, is yet to run on the fastest compounds, with the Italian team opting to do most of their running on the soft compound tires. Sebastian Vettel was fourth fastest with Kimi Raikkonen ninth following his run in the afternoon.

Ricciardo is unsure where Ferrari is in the pecking order, but reckons that the three teams are again likely to be competing for race wins and podiums in the upcoming campaign. The Australian was also confident that Red Bull have made a step forward and is expecting the team to be much closer to Mercedes than it was last year.

“I think that, looking at it now we are close. I still don’t know where Ferrari are, I’m quite confident Mercedes are probably just in front of us but Ferrari I’m not sure. But I think we’re going to be much closer than last year,” the Red Bull Racing driver added.