Daniel Ricciardo and Yuki Tsunoda will stay with AlphaTauri in 2024, sources have told ESPN, leaving impressive rookie Liam Lawson's immediate future in doubt.
Red Bull had been weighing up three options for two seats but are understood to have settled on a decision this week.
The decision extends the F1 career of eight-time grand prix winner Ricciardo, who replaced Nyck de Vries at the Hungarian Grand Prix, for at least one more season.
Ricciardo sees that option as his best path back to Red Bull in 2025, when Sergio Perez's contract will have ended.
The news, which could be announced before Sunday's Japanese Grand Prix, will keep Tsunoda at AlphaTauri for a fourth season but leaves a huge question mark over Lawson's next steps.
AlphaTauri is set to race under a new name and with a closer partnership to Red Bull in 2024, perhaps explaining why Red Bull has chosen the most experienced lineup available.
The team's race lineup for next year has been a big talking point in recent weeks, a decision complicated by the impressive performances of Ricciardo stand-in Lawson across the last three races.
Lawson replaced Ricciardo when the Australian driver broke a bone in his hand ahead of the Dutch Grand Prix.
He impressed at Zandvoort and Monza before scoring the first points of his F1 career at the Singapore Grand Prix, where he finished ninth.
Lawson will race at the Japanese Grand Prix; Ricciardo is hoping to return for the Qatar Grand Prix on Oct. 8.
The only 2024 seat still available is at Williams, who are believed to be considering their options and weighing up the future of underwhelming American rookie Logan Sargeant.
Before his F1 opportunity Lawson had been reserve driver for Red Bull, a role which would be open for him in 2024.
Speaking on Thursday at the media day in Suzuka, Lawson said: "I wouldn't be happy to go back to being reserve but obviously I know how hard it is to get to Formula One.
"And I understand that can be really, really difficult sometimes. So what will happen will happen, but these things I haven't really thought about too much.
"I've just tried to make the most of this [opportunity]."