Kevin Magnussen's position at Haas for 2025 is not secure, warns team boss Ayao Komatsu.
The small American team is unhappy to be losing Nico Hulkenberg at the end of the year, as the German has accepted an offer from Sauber-Audi.
"Nico has been a good reference for how fast our car is," Komatsu told Ekstra Bladet newspaper in Miami. "He is a driver on whose feedback you can develop a car from. His work ethic is amazing.
"We will try to replace him with someone who has the same kind of characteristics. We need that as a team," he added.
Komatsu's comments are concerning for 31-year-old Danish driver Magnussen, who has been with Haas for longer than Hulkenberg.
"Right now we have two vacant seats," Komatsu admits. "One of our current drivers is gone, so naturally that increases Kevin's chances. But I don't want to go into details.
"We need someone who can be a benchmark for the team."
Komatsu acknowledges that Haas is considering Ferrari's top junior prospect, 18-year-old rookie Oliver Bearman, for one of the seats next year. However, the team boss cautioned, "He must deliver in F2, that's clear."
Even if Bearman is selected, Magnussen may not be suited to the role of a reference driver like Hulkenberg for Haas.
Other potential candidates for 2025 include Valtteri Bottas, the current Alpine duo, and possibly Daniel Ricciardo.
"We are still a small team," Komatsu said. "We need a driver who is determined to develop the team with us. Work ethic is important.
"It makes no sense to spend a lot of money on someone who is mega fast but not interested in spending time in the factory and working with the engineers to develop the car."