After setting the pace in practice for the British Grand Prix, Valtteri Bottas' bid for a second successive victory was hit by a five-place penalty on the grid for the Formula One race.
The sanction was imposed due to an unscheduled change of gearbox because it has not been used for six consecutive races.
Bottas, who won the Austrian race last weekend, had outpaced Mercedes teammate Lewis Hamilton in practice on Friday.
Bottas was less than a tenth of a second faster than Hamilton in the afternoon at the Silverstone circuit.
"There is still work to do to get the car more drivable and to be able to trust it more in the high-speed corners," Bottas said. "But overall it was a good start for the weekend. I'm impressed by the new cars on this track with its high-speed corners. They're so much quicker."
Hamilton, who failed to make the podium in the last two races, was competing in front of home fans amid an ongoing backlash for being the only driver to fail to attend a live F1 showcase in central London on Wednesday.
Hamilton's name was jeered when it was mentioned at the Trafalgar Square event, but the three-time world champion reveled in the warm reception at Silverstone.
"It was already one of the very best circuits in the world. But with this car and the speed we are able to carry through the corners, it's just phenomenal, it's like the greatest roller-coaster ride ever," Hamilton said. "Each time I left the garage I gave the fans a wave and I could see them waving back. I just want them to know that I can see them and I really appreciate all the love and support."
Hamilton is looking to re-ignite his title challenge, having slipped 20 points behind leader Sebastian Vettel.
Vettel was fourth fastest in the second practice session, behind Ferrari teammate Kimi Raikkonen, after an experimental transparent screen was removed from the car in the morning. The polycarbonate shield, placed on Vettel's Ferrari for the first time, is designed to protect against flying debris while offering an unrestricted view.
But it made him feel "dizzy" and he was not overly impressed.
"The vision is not very good and it's because of the curvature that creates a bit of distortion," Vettel said. "We had a run plan but I didn't like it too much. I couldn't see much."
The Red Bulls of Max Verstappen and Daniel Ricciardo had gone faster than their Ferrari counterparts in the morning, but they were behind the Italian constructor in the second session.
"Mercedes are very fast, but if we get everything right we can be challenging Ferrari tomorrow," Ricciardo said, looking ahead to Saturday's qualifying. AP
