The 2019 Super Formula switches for Red Bull juniors Dan Ticktum and Lucas Auer have been confirmed in the Formula 1 team's tie-up with the Honda Formula Dream Project.
Ticktum, who finished runner-up in the Formula 3 European Championship to Mick Schumacher and secured a dominant second Macau Grand Prix win this year, has long been regarded as the programme's likeliest next F1 driver.
He did not have the sufficient superlicence points to graduate in 2019 but Ticktum will not make the step up to Formula 2 and will instead race in Super Formula with Mugen.
Ticktum's Mugen team-mate will be Tomoki Nojiri, and the British driver is currently taking part in the series rookie test at Suzuka.
Auer is also testing at Suzuka and will join Ticktum in representing Red Bull in Super Formula, as previously revealed by Autosport.
The nephew of grand prix winner Gerhard Berger, Auer tested with Force India in F1 and has won races for Mercedes in the DTM - but was left without a drive for 2019 due to Mercedes pulling out of the German series.
Auer is now an official part of Red Bull's junior programme and will drive for the new joint-operation between Motopark and B-Max in Japan.
Red Bull has also confirmed the additions of European F3 rookie star Juri Vips and Japanese Formula 4 champion Yuki Tsunoda to its junior roster.
Vips had his first outing as a Red Bull-backed driver in Macau and will join Hitech's line-up in the new FIA F3 series.
The Honda-backed Tsunoda, who showed frontrunning pace in GP3's post-season testing in Abu Dhabi with Jenzer, will continue with the Swiss team in making the switch to FIA F3.
He will also link up with Motopark in European F3's DTM-supporting successor Formula European Masters.
Both the planned Super Formula campaigns and Tsunoda's addition align Red Bull's programme closer with its F1 team's new engine supplier Honda, which has been part of the Japanese manufacturer's plans for next year.
Red Bull said it would reveal more details on its activities in the "coming weeks", which will entail announcements of 2019 plans for Jack Doohan, Dennis Hauger, Jonny Edgar and Harry Thompson - the four young drivers who made up its late-2017 intake.
No mention was made of American racer Neil Verhagen, who was part of the roster this year and finished 11th in the Formula Renault Eurocup.