McLaren’s Fernando Alonso has been barred from racing in the Bahrain Grand Prix on medical grounds following his 180mph crash in Australia.
Doctors at Sakhir found problems with the Spaniard’s chest after conducting scans on the two-time world champion.
He will be replaced by McLaren reserve driver Stoffel Vandoorne, who will be making his F1 debut in Bahrain.
Alonso, 34, will have to be checked again before the Chinese Grand Prix in two weeks.
Governing body the FIA said Alonso’s chest scans “showed insufficient resolution of the signs to allow him to compete”.
Alonso is to take part in the official news conference on Thursday, where he will further explain the doctors’ findings.
He spent an hour and a half with FIA doctors after arriving in Bahrain on Thursday, undergoing the standard checks for any driver who has suffered a heavy crash.
Alonso’s car rolled and landed upside down after he hit the back of Haas driver Esteban Gutierrez’s car in Melbourne on 20 March.
The Spaniard has complained of sore ribs but had emerged from the check saying he felt otherwise OK and wanted to race.
His McLaren-Honda team have had to prepare a new chassis and engine for this race as a result of the extensive damage incurred in the accident.
Vandoorne, a 24-year-old Belgian, is the reigning GP2 champion – the level below F1 – and one of the most highly regarded drivers not to have a regular F1 drive.
He will fly overnight to Bahrain from Japan, where he has been this week testing the car he races in their Super Formula series.
Vandoorne tweeted: “About to board for Bahrain, a bit earlier than expected but so much looking forward to it. Will do my very best for the team.”
He is a possibility to replace Britain’s Jenson Button as Alonso’s team-mate in 2017 and racing this weekend provides him an opportunity to showcase his abilities.