How Formula 1 teams will handle a rule about using rookie drivers in practice sessions this season is unclear.
It is now known that, to comply with the regulations requiring every race driver on the grid to give up his car on an official Friday, Robert Shwartzman will take the wheel of Carlos Sainz's Ferrari at Zandvoort.
"We let our drivers decide for themselves when they want to take the break," said team boss Frederic Vasseur.
Frederik Vesti will be in action in a Mercedes in Mexico - and many insiders think that will also be the scene of a lot of other teams catching up with the rookie rule.
That's because there aren't a lot of other sensible opportunities for the teams to comply.
For instance, the alternative tyre allocation rule will again be in play in Monza, and there are three more sprint weekends to come - in Qatar, Austin and Brazil - where there is only a single practice session before qualifying.
Las Vegas, meanwhile, is a brand new street circuit for Formula 1, while the demanding Singapore layout is also regarded as inappropriate for the rookie outings.
That leaves only Suzuka and Abu Dhabi as other viable locations yet to be raced. It is believed Charles Leclerc, for instance, will give up his cockpit at the 2023 finale.
Ferrari, though, will not use its juniors Oliver Bearman or Leclerc's younger brother Arthur. "They should first concentrate on the end of the Formula 2 season," said Vasseur.
It is thought that one of them will be loaned to Ferrari-powered Haas for a rookie outing.
McLaren, Alpha Tauri and Williams, however, have already partly complied with the rookie rule - by fielding rookies (Oscar Piastri, Nyck de Vries and Logan Sargeant) as race drivers this year.
