Ferrari's Charles Leclerc topped the time sheets in first practice for the season-ending Abu Dhabi Grand Prix but has been hit with a 10-place grid penalty for Sunday's race where Ferrari are fighting with McLaren for the constructors' title.
Leclerc required a new battery which took him over the allowed limit for the season. It is a big blow for Ferrari who trail McLaren by 21 points, with 44 points still up for grabs.
The bad news came on a Friday when Leclerc and his brother, Arthur Leclerc, became the first siblings to compete for the same team at a world championship weekend in the sport.
Charles Leclerc clocked 1 minute 24.321 seconds on the 5.281-kilometre Yas Marina Circuit.
He finished .221 of a second ahead of McLaren's Lando Norris, with Lewis Hamilton starting his last weekend in a Mercedes with third place, .485 off the top, before a 2025 switch to Ferrari.
Arthur Leclerc trailed his brother by 1.858 seconds in Carlos Sainz' car. He was one of six rookies to drive on Friday, with Aston Martin's Felipe Drugovic their best in ninth.
Red Bull's Max Verstappen, who clinched a fourth straight world title two weeks ago, was among regular drivers to sit out the session.
Isack Hadjar took his place ad finished 15th amid speculation that the Frenchman could possibly get a permanent place next year at sister team Visa RB - if Sergio Perez is not retained at Red Bull and Yuki Tsunoda or Liam Lawson are promoted from RB.