ABU DHABI (AFP) - Max Verstappen topped the times for Red Bull ahead of both Mercedes cars in Saturday's (Nov 30) closely-contested third and final practice for Sunday's Abu Dhabi Grand Prix.

The top three were separated by less than a tenth of a second at the Yas Marina circuit where the Dutchman clocked a best lap in 1min 36.566sec, 0.074 of a second ahead of Lewis Hamilton in the leading Mercedes.

The six-time champion's Mercedes team-mate Valtteri Bottas, who is set to start from the back of the grid after taking another new power unit overnight, was third ahead of Alex Albon in the second Red Bull.

The Ferraris of Sebastian Vettel and Charles Leclerc were fifth and sixth running on medium tyres to set their times ahead of Racing Point's Sergio Perez, Renault's Daniel Ricciardo, Carlos Sainz of McLaren and Pierre Gasly of Toro Rosso.

At the other end of the lap times, Williams' George Russell outpaced his team-mate Robert Kubica to confirm his recovery from illness, rising to 19th as the former champions continued to fill the back row of the provisional grid.

Bottas, who had taken a fresh engine on Friday, had another new one fitted because of reliability fears after problems were detected following opening practice.

"I still want to fight for the pole, even though I would not keep it," he said. "That would be good fun and with a fresh engine as well, but the main focus just has to be the race pace because we know we're going to start from the back."

In another overnight development, it was confirmed that Mercedes' test and reserve driver Esteban Ocon has been barred from the team's garage.

He will race for Renault next year as successor to Nico Hulkenberg alongside Daniel Ricciardo and is set to test for them next week in the post-season event in Abu Dhabi.

The highly rated 23-year-old Frenchman explained why he was absent from Mercedes' garage.

"Technically, I do not have that right, but we are discussing and I have been able to fit my seat, prepare myself a little and go in the simulator.

"That's why I do not have the right to be in the (Mercedes) garage this weekend. We are preparing to test next week and I'm lucky to have two days, which is rare.

"Even Daniel (Ricciardo) did not have this chance last year, so it's going to be a good preparation for next season."