Norris to start 15th at Azerbaijan GP as Hamilton drops to pit lane
Seven-time world champion Hamilton had qualified seventh, one behind Red Bull's championship leader Max Verstappen, but will now join Alpine's Esteban Ocon in starting from the pit lane after exceeding his power unit allowance.
Mercedes also made changes to the set-up of Hamilton's car, the FIA technical delegate Jo Bauer said in a report referring the matter to stewards.
"Lewis will take a new power unit ahead of today's race and will therefore start from the pit lane," a team spokesman said.
"Having lost a power unit in Australia earlier this season, we knew we would have to introduce a new power unit into the pool for Lewis at some point this season. We've opted to do so today."
Norris qualified 17th on Saturday after a yellow flag interrupted his last flying lap in the opening phase but had moved up to 16th after Alpine's Pierre Gasly was disqualified for a fuel flow irregularity.
The McLaren driver is second in the championship but 62 points behind Verstappen and Sunday's race already looks like damage limitation for him.
Ferrari's Charles Leclerc starts on pole position with McLaren's Oscar Piastri alongside on the front row at a circuit with good overtaking opportunities.