Pierre Gasly will start the Azerbaijan GP from the pit lane after being penalised for failing to stop at the weighbridge after Practice Two.
The Frenchman, who had finished ninth in the session, failed to spot his number had been indicated to stop for a mandatory weight check and continued to his Red Bull pit box.
The team then completed a practice pit stop, changing all four tyres, with the FIA deeming he had broken the rules and handing him a pit lane start.
- P2: Leclerc and Ferrari streak ahead
- Hamilton vs Magnussen: What happened?
- Getting to know the real Vettel
The Stewards' verdict read: "The Stewards reviewed video evidence and heard from the driver of car 10 (Pierre Gasly) and the team representative and determined that the driver failed to stop for weighing when required to do so.
"Instead, he drove on and proceeded to do a pit stop where the car was worked on by lifting the car and all four wheels were changed, in breach of Article 29.1 a). Under Article 29.1 a) the penalty for this infringement is specified to be for the car to start from the pitlane and we so order."
Red Bull have the right to appeal the penalty, but it continues a difficult start to Gasly's career at the team following his promotion from Toro Rosso.
The 23-year-old has struggled to match the pace of team-mate Max Verstappen and was half a second slower than the Dutchman in Baku practice.
Speaking to Sky F1 before his penalty, Gasly had felt confident Red Bull had a strong race car for the weekend.
"A really intense FP2. We tried to do some short runs, long runs," he said.
"We have a pretty good race car, we are happy with the high fuel runs. A good base to start from."
Watch the Azerbaijan GP live on Sky Sports F1. Sky Sports is the home of live and exclusive F1. Find out more here to watch the 2019 season live