The Mexican currently has a contract for next year, and Red Bull team boss Christian Horner has repeatedly insisted that Perez will remain alongside Verstappen in 2024.
However, speaking to Austrian outlet Kleine Zeitung, Marko has denied that it is a certainty Perez will embark on a fourth campaign with the reigning World Champions next year.
“Nothing is 100 per cent certain in Formula 1, it just doesn’t exist,” the Austrian said regarding Perez’s position. “There are always performance-related situations somewhere that need to be discussed.
“We’ll take a look and discuss how to proceed in Zandvoort, then we’ll know more.”
Perez’s performances did improve towards the end of the first half of the season, though, delivering successive podium finishes in Hungary and Belgium.
Heading into the final 10 rounds, Perez retains a 40-point advantage over Fernando Alonso in the battle to finish behind Verstappen. Red Bull is aiming to have its two drivers finish first and second in the Drivers’ Championship for the first time.
Marko believes that Perez’s chances of consolidating his current position have been bolstered by the nature of the pecking order consistently changing behind Red Bull.
“Our biggest advantage is that the pursuers are constantly changing, which automatically makes us appear stronger and the chances for Checo also increase,” he added.
The pressure on Perez’s seat has ramped up considerably since Daniel Ricciardo completed his full-time F1 comeback with Red Bull’s second-string side, AlphaTauri.
Ricciardo has confirmed his return has come with the intention of returning to the Red Bull seat that he vacated at the end of 2018.
And Marko has fuelled further speculation by confirming that he met up with the Australian during the summer break: “We saw each other, that’s clear when he comes to Graz.”
Aside from impressing with his on-track test at Silverstone in the Red Bull RB19 earlier this year, Marko adds that Ricciardo’s technical feedback will be critical to aiding AlphaTauri’s attempts to move off the bottom of the Constructors’ standings.
“There will be a major update at AlphaTauri and you will see whether the direction is right,” he explained. “We hope that will be the case and that it will soon be possible to score points.
“A driver like Ricciardo will of course help you in this situation enormous, it tells you exactly what is good and which updates are useless.”