Valtteri Bottas deprived Lewis Hamilton of the honours for a Mercedes 1-2 in Friday's Russian Grand Prix practice at Sochi where Red Bull announced Max Verstappen will have to start Sunday's race at the back of the grid for fitting his car with a new engine.
Verstappen, who leads by five points going into the 15th round of the white-knuckle title fight with Hamilton, has already used up the season's quota of three power units.
The team announced the Dutch driver would take the hit in a race where he was already facing a three-place grid penalty.
That sanction stems from an incident in the last race in Monza where he was found "predominantly" to blame for a crash with Hamilton.
The seven-time champion began the weekend where he is targeting his fifth Sochi win and 100th overall being shaded by his Alfa Romeo-bound teammate.
The second session went the way of the morning's opening practice with the Finn leading the time sheets with a 1min 33.593 lap at the circuit in the Olympic Park.
AlphaTauri's Pierre Gasly, Lando Norris for McLaren, and the Alpine of Esteban Ocon completed the top five.
Verstappen, 1.28 off the pace, took sixth.
The Dutch driver will have Charles Leclerc for company at the back of Sunday's grid after an engine change to his Ferrari.
It was a routine two sessions for most of the drivers but not McLaren's Lando Norris who crashed on the way back to the pits in the morning and Alfa Romeo's Antonio Giovinazzi after lunch.
The Italian crashed at Turn Nine, bringing out the red flag.
One man happy to be back on the track despite only posting the 12th fastest time in second practice was Kimi Raikkonen after the Alfa Romeo driver missed the last two races following a positive Covid-19 test.
The sessions were blessed with sunshine but heavy rain is forecast for Saturday's third practice and qualifying.
With the washed-out Belgian Grand Prix still fresh in the mind, organisers have taken steps to ensure lightning doesn't strike twice by arranging for qualifying to be staged on Sunday morning should it be impossible to go ahead in its traditional slot.