Max Verstappen led team-mate Sergio Perez to complete a practice treble at the Saudi Arabian Grand Prix as Aston Martin's Fernando Alonso remained Red Bull's closest challenger.
The reigning world champion continued his dominant form by recording a 1:28.485 to finish more than 0.6s ahead of Perez, with Alonso just short of a second behind the Dutchman in third at Formula 1's fastest street circuit in Jeddah.
While Red Bull have established themselves as heavy favourites for both qualifying later on Saturday and Sunday's race, the battle behind them promises to be thrilling with just half a second covering Alonso and the 12 cars that finished behind him.
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Lance Stroll underlined Aston Martin's strength by slotting in behind Alonso in fourth, while Lewis Hamilton improved on his Friday showing to end fifth for Mercedes.
Charles Leclerc, who will receive a 10-place grid penalty in Sunday's race after taking on new parts, was sixth but Ferrari did little to smooth fears over their reliability as both of their drivers appeared to operate with their newly-fitted power units for this weekend running well below full capacity.
There was finally some encouragement for McLaren as Lando Norris finished seventh, a place - and just a few thousandths of a second - ahead of rookie team-mate Oscar Pisatri.
Pierre Gasly showed enough to suggest Alpine can be part of what promises to be a hugely unpredictable qualifying contest, finishing ninth ahead of Ferrari's Carlos Sainz and Mercedes' George Russell.
The session's big losers were AlphaTauri, who were unable to send Nyck de Vries out on track after a technical issue left them needing to change his power unit, while team-mate Yuki Tsunoda was last among those who set times.
The late-afternoon session provides an imperfect indicator of how qualifying will shake out under the lights later on Saturday, but the fact that the track temperature dropped amid heavy cloud cover made conditions more representative.
After leading a dominant Red Bull one-two at the opening race of the season in Bahrain earlier this month, Verstappen looks set to continue a dream start to a campaign he hopes will yield a third successive drivers' title.
"Sergio is still a big chunk off Max as well," Sky Sports F1's Damon Hill said. "It does point towards a total dominance here by the Red Bulls and Max, so we're going to have to hope for some battles behind them."
With Ferrari appearing unsure of their engines and Mercedes looking to rebuild after accepting they have taken the wrong path with their design concept, it's Alonso and Aston Martin who appear best placed to take advantage of any Red Bull mishaps.
The only discomfort Verstappen experienced in final practice was self-inflicted, with the Dutchman almost causing a crash as he failed to get out of the way of the fast-moving Norris while going slowly on the approach to Turn 8.
Verstappen pulled alongside Norris to apologise, and faced no punishment for an incident that drivers would be penalised for if it occurred in qualifying.
Formula 1 street racing is back! Watch the Saudi Arabian Grand Prix live on Sky Sports F1 this weekend. Saturday's qualifying and Sunday's race are live at 5pm. Get Sky Sports