Lewis Hamilton expects it to be a “real challenge” for Mercedes to beat Red Bull in the 2018 Formula 1 season.
Mercedes technical director James Allison said on Wednesday that there is “no doubt” Red Bull has re-emerged as a title threat after it lagged behind both Mercedes and Ferrari in 2017.
It follows Daniel Ricciardo’s unofficial lap record around the Barcelona track, which was bettered by nearly a full second by Ferrari's Sebastian Vettel on Thursday, the penultimate day of pre-season running.
Hamilton was only ninth-quickest on Thursday after an afternoon spent working on long runs, but said the evidence was pointing towards a close fight for championship honours – and that Red Bull in particular looks menacing.
“The ultimate goal is that we hopefully have more teams fighting for the championship,” said Hamilton. “That's only good for the sport.
“I'm really hopeful, and I think Red Bull could be a real challenge this year.
“Their car looks great, and I've not really seen anything of the Ferrari but I'm sure that's good as well. It’s really exciting.”
Like Hamilton, Verstappen did not elect to focus on single-lap pace on Thursday, ending up only 12th-fastest.
The Dutchman emphasised Red Bull’s goal would be to get within three tenths of Mercedes’ qualifying pace in order to challenge the Brackley squad.
Verstappen said: “Well, I think, first of all, we have to be closer.
“Once we are within three tenths, four tenths, in qualifying, then at least you can fight them [Mercedes] in the race, because normally I think in the race it should be a bit closer.
“So, we're definitely targeting to be in those three tenths.”
Hamilton "hopes" Vettel laptime strong
“I don't know if that's a good time,” said the reigning champion. “I don't know if it's a qualifying run, I don't really care. It's testing. It's really irrelevant, whatever the time.
“What matters is where we are in qualifying, in Q3 in the first race, when everyone's on lower fuel. We've not been on lower fuel yet, so I have no idea where the car can go.
“I hope [Vettel’s lap] is good, I hope it's a good time so that means that they're strong, and that means that we've got a race on our hands.”
Asked about Vettel’s lap, Verstappen replied: “It's a good laptime, for sure.
“But we knew that they were going to be strong anyway, and Mercedes will be very strong as well. We just try to be very close.”
Additional reporting by Erwin Jaeggi