Max Verstappen talks to journalists at Catalunya. Picture: Francisco Seco / AP

Barcelona, Spain - Max Verstappen doubts Renault and McLaren will be a threat to his Red Bull Formula One team this season despite all three former champions now having the same engines.

Red Bull finished third overall in 2017 while Renault was sixth and McLaren, then with unreliable Honda engines, a distant ninth. Both Renault and McLaren are tipped to make big improvements but Red Bull has looked stronger in testing and Verstappen made clear on Thursday that his focus was on Ferrari and champion Mercedes.

"You pay attention to everybody, but I don't think they will be our main rivals," the 20-year-old Dutch driver told reporters at the Circuit de Catalunya when asked about the other Renault-powered teams. "And we don't want that to be the case as well, because that would mean we are not doing such a good job. We need to look (at those) ahead."

Verstappen on track during the second pre-season test session at the Circuit de Catalunya Picture: Manu Fernandez / AP

Verstappen won two races in 2017 while Australian team mate Daniel Ricciardo also took a win in Azerbaijan. The team, which last won a title in 2013 with Sebastian Vettel, has sounded increasingly upbeat about its 2018 car as testing has progressed.

Ricciardo will be out of contract at the end of the year and has been linked in media reports to both Mercedes and Ferrari for 2019. Red Bull, which has Verstappen signed up to the end of 2020, wants to keep Ricciardo in what is one of the most exciting pairings on the starting grid.

Red Bull's motorsport consultant Helmut Marko said a time frame had been decided.

"We agreed with him a deadline," Marko said. "So as soon as this deadline is over we'll tell you if it's yes or no."