Max Verstappen and Charles Leclerc will each start from the back of the grid at the Belgian Grand Prix after receiving penalties following power unit changes.
Verstappen leads Ferrari rival Leclerc by 80 points in the Formula One drivers' championship, having won eight of the 13 races so far this season.
However, the Red Bull man, who came from 10th on the grid to win the Hungarian Grand Prix prior to the mid-season break, will have to fight his way through the field to triumph at Spa-Francorchamps on Sunday.
Verstappen won in Belgium last year in a race reduced to two laps behind the safety car because of a deluge that made racing unsafe.
The Dutchman, who was born in Belgium under two hours away from the circuit, has had all the components of his power unit replaced.
Leclerc, meanwhile, has taken on a fifth power unit of the season as well as a new gearbox.
Joining the title rivals at the back will be McLaren's Lando Norris, Alpine's Esteban Ocon, Haas driver Mick Schumacher and Valtteri Bottas of Alfa Romeo.
Norris, Ocon and Bottas have seen their teams opt to change their engines, while Schumacher is taking on a new control electronics unit.
The grid shake-up could put Mercedes in position to claim their first win of a difficult season, while Verstappen's team-mate Sergio Perez and Leclerc's fellow Ferrari driver Carlos Sainz will each fancy their chances of winning for the second time in 2022.