Former Ferrari performance engineer Steven Petrik was installed as a replacement for Bottas' engineer Alex Chan, whom the Finn had worked with since joining the team in 2022.
Bottas noted that the decision was "not in my hands", suggesting that this was part of Audi's "reconstruction" of the Sauber team ahead of the German brand's entry as a full works outfit in 2026.
Sauber representative Alunni Bravi revealed that this was largely the case, and that CEO Andreas Seidl had been making changes that would move the team towards its final structure when the rebrand is completed at the end of 2025.
"Andreas Seidl decided to anticipate certain decisions, and start implementing the changes that will bring the current structure towards the final structure that we will have in place in '26," Alunni Bravi explained.
"But we needed to start implementing those changes. This is not the final structure of the race team. As in Hinwil there is not the final structure of what we will be the Audi F1 team and the organisational chart.
"We wanted to start, and Andreas Seidl decided to do it immediately. Because we think that we need to bring a bit more experience, but also to bring people that can have know-how from other teams, from top teams and help us to develop our processes, our analysis."
Alunni Bravi added Petrik's introduction as race engineer to Bottas had started at the Pirelli test following the Japanese Grand Prix, and that the team had let Bottas know the decision after China.
He added that, although the addition of Petrik arrived in the same week as the team's announcement that Nico Hulkenberg would join the team in 2025, the two signings had "no connection".
"Of course, it's now up to us to integrate the new engineer, and also, of course, to create, to establish a good working relationship, but also personal relationship between Valtteri and race engineer.
"We discussed this with Valtteri after China. There was a meeting immediately after the race. Steven Petrik was already race engineer of Valtteri in Suzuka during the two Pirelli test days.
"And we decided to anticipate this change. Of course, when you take a decision, you can always take a good or a bad decision - and only the time will prove if we have been good in taking this one.
"But this... there was no link between the change of the race engineer and the announcement of Nico [Hulkenberg]. It was just one of the first steps that we wanted to implement, to have a new organisation also in the race team coming into place as soon as possible."
