Reigning world champion Max Verstappen has topped the time sheets on the final day of pre-season testing before the season's first grand prix next weekend.

Verstappen's time of 1 minute 31.720 seconds was the quickest around the Bahrain circuit, half a second faster than any other driver.

Despite lighting up the time sheets, Verstappen was quick to hose down any suggestion that the teams were going all out during the final testing session before the start of the year.

The world champion said he was not focusing on his lap times in Bahrain and was more concerned with how the new car was performing.

"No one gives full beans or goes to qualifying spec at testing, so we can't read too much into the timing screens," he said.

"The new parts we tested today worked well, which is what we always hope for.

"The main focus today was testing the tyres we are going to use next week."

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While there were plenty of positives for the Red Bull garage the same could not be said for McLaren, whose three-day test was compromised.

Daniel Ricciardo's COVID-19 diagnosis meant only Lando Norris drove for the team based out of Woking in the UK.

Ricciardo is expected to line up for next week's season-opening Bahrain Grand Prix, but he will race with limited time in the new car.

For Norris, his weekend was hampered with issues to his car that kept him off track for long stints.

McLaren team principal Andreas Seidl said the issue on Norris's car involved the front axle.

"Time constraints did not allow us to entirely solve this during the test," Seidl said.

"The objective is to fully solve this issue before next weekend's Bahrain Grand Prix."

Norris, who finished 40 points ahead of his Australian teammate in the drivers' championship last season, said the team has a lot to catch up on before next weekend.

"There's still a lot of improvements to be made for us to able to compete next week," he said.

"A tough three days, not what we wanted but good enough. We've learnt a lot and made the most of it, which is the most important thing."

The Bahrain Grand Prix will be held on Monday, March 21, at 2am AEDT.