Valtteri Bottas was handed a reprimand for causing a collision on Friday as he topped the times ahead of team-mate Lewis Hamilton in a Mercedes one-two in opening practice at the Abu Dhabi Grand Prix.
The 30-year-old Finn completed a 'double top' by going fastest in both sessions, making full use of a new power unit after suffering an engine failure in Brazil two weeks ago. The switch is costly however as he will take penalties that send him to the back of the grid.
Bottas tried to pass Romain Grosjean on the inside at Turn 12, but the Haas driver turned in and the pair collided. They were not hurt.
"I think he didn't really see me coming up the inside," said Bottas. "My apologies, but there was nowhere for me to disappear. I went for the over-take and that was it.
"Honestly, I thought he would see me coming. He wasn't covering the line so I thought he was aware I was there, but maybe he didn't look in the mirror before turning in.?
Both drivers were called to the stewards who later issued a statement that said Bottas had "acknowledged that it was a failed attempt at an overtake which resulted in the collision".
It was his first reprimand of the year.
Hamilton said he was using the final practice sessions of the season to find potential set-up improvements for next year.
"I am pushing the car into a different place over the last two races just to explore," he said. ?It is easy to go too far, but I am sticking with it and hoping that it works.
"We already know what does work and I am not keen to do what does work -- I am really trying to see where else I can exploit the car and the tyres."
- 'Explore' -
He added: "I am definitely hoping to unlock something and utilise a couple of different tools that I haven?t touched during the year because they never really worked before.
"I am trying to explore and see whether or not I can get them to work. It is a pre-emptive thought for next year even though next year?s car is going to be different.
"There still might be things I can apply but I am having to take it all with a pinch of salt at the moment."
Hamilton has won four times in Abu Dhabi.
Bottas, who was quickest ahead of Red Bull?s Max Verstappen in the opening session, followed that up by outpacing Hamilton in the later ?twilight? session as Mercedes produced a resounding one-two.
Bottas produced a best lap in one minute and 36.256 seconds to wind up 1.578 seconds clear of Hamilton, his speed and determination betraying his wish to put the travails of his private life behind him. He announced on Thursday his three-year marriage to fellow Finn Emilia Pikkarainen was over.
After a slow morning, Charles Leclerc was third ahead of his Ferrari team-mate four-time champion Sebastian Vettel, who arrived late on Friday morning ahead of the session following the birth of his third child, a son, on Wednesday.
The Red Bulls of Max Verstappen and Alex Albon were fifth and sixth ahead of Grosjean, Racing Point?s Sergio Perez and the Toro Rosso pairing of Daniil Kvyat and Pierre Gasly.
Hamilton on his way to second in Friday's practice behind his Mercedes teammate Bottas
Bottas apologises after Grosjean collision