Sauber chief Alunni Bravi has been astonished by Alfa Romeo drivers Valtteri Bottas and Zhou Guanyu since they joined the team.
The former Mercedes man and ex-Formula 2 race winner joined forces in 2022 after Kimi Raikkonen retired and Antonio Giovinazzi wasn't offered a new deal.
They helped the Swiss-Italian team reach sixth in the constructors' standings last year with measured consistency, and Bravi was full of praise for both for the jobs they have done for the team.
“Zhou did a step last year and he did another step this year. What has impressed me is his mindset, he doesn’t do any mistakes," said Bravi to F1 Unlocked.
"He has a good technical understanding of the car, he is talented and he is fast. Each year, you need to improve. For me, he’s been impressive from the very first race.”
Bravi also praised Bottas' 'winning culture', having left the champion team Mercedes at the end of their dominant era from 2017 to 2021.
“He’s helping our team to do a step,” adds Bravi. “He was important for us last year to have his winning culture.
"His presence each week coming to the workshop, working with the engineers, working in the simulator, having the speeches with the employees and working with Zhou – it was clear and it was important.”
READ MORE: Nico Rosberg: Sky F1 pundit and former world champion