The signs are growing by the day that Sergio Perez should be very worried about the validity of his Red Bull contract for 2024.

Red Bull bigwigs Dr Helmut Marko and Christian Horner are now making consistently pessimistic public comments about Mexican Perez's flagging form.

"We have a contract and we want to fulfil it," 80-year-old team consultant Marko is quoted by the Austrian broadcaster ORF.

However, he also warned that Red Bull has a very healthy roster of contracted drivers vying for Perez's seat, having already indicated his interest in McLaren's Lando Norris.

"We have three drivers in Alpha Tauri and (Liam) Lawson is the reserve driver of the four cars," he said.

"Many things can happen in that, but although not particularly related to Perez, it is logical that sooner or later Lawson will have a seat in F1."

Austrian Marko also told Kronen Zeitung newspaper: "It's not working with Perez at the moment.

"I hope we can save second place," he added, referring to Red Bull's last remaining goal for the 2023 season - the first time the team has finished both first and second in the drivers' standings.

"Checo has to deliver now," said Marko.

"Now that McLaren has two such strong drivers at the wheel, his performance becomes critical. For a while, Perez's position looked quite comfortable, but now the lead is disappearing like snow in the sun," he added.

Marko said Perez's place at Red Bull wasn't an issue when he was performing better and the team had no consistently challenging team among Mercedes, Aston Martin, McLaren and Ferrari.

"It wasn't a problem when we didn't always have the same pursuers in the race," he said. "Now it's becoming critical."