"They can be favourites if they want," Hamilton told reporters on Sunday when asked about the Red Bull performance. "I mean, they're looking strong.

"I don't really focus on that kind of stuff and they've had some really good running ... both the drivers have been looking quite strong.

"They're going to be a different machine or animal this year with, I think, a really good, strong line-up for two drivers and a really good car."

Max Verstappen topped the timesheets on Friday to open the three-day test and newcomer Sergio Perez went fastest on Sunday morning before handing over to the Dutchman.

Verstappen and Hamilton were out together in the second session with the Briton coming off a clear second best to the 1 minute 28.960 seconds of his rival - the only time below the 1:29 mark and pursued closely only by Yuki Tsunoda of sister team Alpha Tauri.

Hamilton had to settle for fifth with 1:30.025 but being sandwiched between the Alfa Romeo of Kimi Raikkonen and Williams of George Russell is modest indeed for the F1 record race winner.

Hamilton said he was also impressed by McLaren, who are looking to build on third place in the constructors' championship last season and now have Australian Daniel Ricciardo on board.

After topping the time sheets on both the first two mornings of testing, Ricciardo was seventh fastest on Sunday afternoon in 1:30.144.

The good news for Mercedes was Valtteri Bottas topping the sheets on Saturday after gearbox problems limited running on day one.

"It's so hard to say at the moment where we are, where other teams are, and obviously we don't know their run programme, what engine modes they're running and what fuel load - but I have a feeling it's going to be close," said Bottas.

Mercedes definitely have work to do in the two-week window before the Bahrain Grand Prix opens the season in place of the Australian race which has been delayed due to the coronavirus pandemic.

"It's better that it doesn't go smooth now and goes smooth once we get into the racing scene," said Hamilton.

"So this is the perfect time for us to find the issues and have the problems. And so I welcome that."

Australian Associated Press