Charles Leclerc was the driver to beat in first practice for this weekend's Hungarian Grand Prix before his session came to an end in the closing stages.
The Monégasque came on the radio to say that "something has broke" before his mechanics wheeled his smoking Ferrari back into the garage.
Red Bull's Max Verstappen was 0.484 seconds off Leclerc's pace, and Lewis Hamilton in the other Ferrari finished third.
Hamilton had a few issues himself and came on the radio during the session. He said: "Something is wrong with the upshifts, and downshifts. Like downgraded upshifts and downshifts all the time."
Verstappen's teammate Isack Hadjar crossed the line in fourth, and George Russell rounded out the top five.
Russell will be looking to bounce back after he retired from the Belgian Grand Prix following a collision with Hamilton in the opening lap last weekend.
The Brit has failed to score points in three out of 10 rounds this season. His teammate Kimi Antonelli didn't taking part in the session as rookie Fred Vesti replaced the title leader, as per the rules, finishing in seventh.
Aston Martin's Lance Stroll brought out the red flag with 20 minutes of the session to go with a "left-rear suspension failure." His teammate Fernando Alonso finished 13th.
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The team has come equipped to Budapest with a 16-part car upgrade.
Chief trackside officer Mike Krack spoke to media in the paddock on Thursday and said: "I think we are all realistic. We have a plan and we work to that plan. Success and setbacks are part of sport.
"I think we have been in a difficult situation or difficult spot before, and we try to get out of it, but there are more steps needed. This is part of the development strategy, so I would not call it a make-or-break. It is just the development that needs to continue."
Gabriel Bortoleto and Nico Hülkenberg finished sixth and eighth respectively in the Audi. Racing Bulls' Arvid Lindblad and Liam Lawson took the two final spots in the top 10.
Second practice takes place on Friday at 4 p.m. BST.
