Now, 23-year-old Kvyat is flying the flag for Russia and, according to Red Bull chiefs, stands a good chance of keeping his place for 2018 at the junior team Toro Rosso.
"As a F1 driver, no-one is immune from the risk of being replaced at any moment," Petrov told Russian broadcaster Match TV.
"So even if Christian Horner is saying they want to extend the contract, [Kvyat] cannot be complacent. I remember driving for Renault and Nick Heidfeld was very strong, and yet the team changed during the season to Bruno Senna.
"So I think Daniil needs to have a good rest now, reboot and get ready for the second part of the championship. If there are similar accidents as we saw in the first half, then everything can end badly for him."
The season resumes on August 27 with the Belgian Grand Prix.