Daniel Ricciardo topped the times for the re-branded RB team, formerly Alpha Tauri, in Thursday's first practice at the season-opening Bahrain Grand Prix, the Australian beating both McLarens in a windswept session at Sakhir.
Grumbling world champion Max Verstappen wound up sixth for Red Bull, but the action provided few clues to likely pace and form for Saturday's race that kicks off an unprecedented 24-race campaign.
Ricciardo clocked a best lap in 1min 32.869sec when running on softs late in the hour's action to finish on top ahead of McLaren's Lando Norris and Oscar Piastri with Yuki Tsunoda fourth in the second RB.
Two-time world champion Fernando Alonso was fifth for Aston Martin ahead of Verstappen, Mercedes' George Russell, Charles Leclerc in the leading Ferrari and his future team-mate Lewis Hamilton in the second Mercedes.
Valtteri Bottss was 10th for Alfa Romeo ahead of Carlos Sainz in the second Ferrari and Sergio Perez in the second Red Bull.
After a morning of excited talk about the outcome of Red Bull's investigation into team boss Christian Horner’s conduct, following complaints of inappropriate behaviour, the opening session of 2024 began with the champion team taking their usual grip of events on track if not off it.
Horner was clearly relieved that the case against him and all complaints had been dismissed as he made his first public appearance at the Bahrain International Circuit this week ahead of the action.
"I am just pleased the process is over," he told Sky Sports.
"I obviously can’t comment about it, but I am here and this is very much the focus now, on the Grand Prix, and the season ahead and trying to defend both of our titles."
When asked if he regretted that the case was made public and not kept in house, he said: "Again, I'm not going to be able to give you any further comments on it, I'm afraid.
"But I am pleased to be here in Bahrain with the team and focused on the season ahead."
'Everything is miles off'
On a perfect but windy day at Sakhir, the air temperature was 20 degrees Celsius and the track 36 as the action began with Bottas leading the way for Sauber.
Verstappen came out after seven minutes with the lead changing rapidly as the drivers and teams settled into a rhythm on the highly abrasive circuit in breezy conditions.
The 26-year-old Dutchman took command after 12 minutes with a fastest lap in 1:33.900, the first below 1:34 and six-tenths quicker than Sainz in the leading Ferrari.
As is his custom, the champion was soon complaining about his car, the new RB20.
In an expletive message on team radio he said "everything is miles off!"
The team made a front wing adjustment when he pitted.
Russell briefly replaced Verstappen on top, but he responded immediately to trim his lap to 1:33.535 before McLaren switched to soft tyres, Piastri and then Norris taking over at the top of the times in 1:32.901.
As others followed, on to softs, Ricciardo clocked a quickest lap in 1:32.869 with RB team-mate Tsunoda going fourth, a hint that Red Bull's junior outfit may have more potential than expected.
With 12 minutes to go, the Australian remained on top, but without any soft-tyre laps from the 'big three' teams and many drivers continuing to evaluate hard and medium compounds for long runs.
At this point, Verstappen was sixth and Perez 12th, with Hamilton in between in ninth, ample proof that the session offered any decisive evidence of form and pace for the year ahead.
Agence France-Presse