F1's Sauber confirm Bortoleto to race next year as Bottas and Zhou depart
McLaren junior Bortoleto will team up with the more experienced Nico Hulkenberg, aged 37, in 2025.
The 20-year-old Bortoleto currently tops the F2 standings.
"This is one of the exciting projects in motorsport, if not in all sports," Sauber, which will become the Audi entry in 2026, quoted him as saying.
"Joining a team that combines the rich motorsport history of Sauber and Audi is a true honour."
Bottas and Zhou are set to depart at the end of the season after neither registered a point in the driver's championship this campaign so far.
"After open and constructive discussions with Valtteri Bottas and Zhou Guanyu, we mutually concluded that conditions to continue together could not be met so we agreed that it is time to part ways," Sauber said.
"We would like to thank both for the contribution they have made to the team in the last three years.
"They have been the embodiment of professionalism, using their experience and enthusiasm to support our growth."
It is unclear what the future holds for the 35-year-old Finn Bottas, a former Williams and Mercedes driver, and the 25-year-old Zhou.
Last month, Bottas said he would consider returning to Mercedes as a reserve driver next year if he was not retained by Sauber.
Sauber had made Zhou China's first Formula 1 driver.
"Sadly the last two seasons have been challenging for all, but I want to look forward," Zhou said in a statement Wednesday.
He added: "I am now discussing a number of options to stay in the Formula 1 paddock."
