"Some small issues for me today, but nothing big. Mark unfortunately had to stop and couldn't finish the practice, it looks like his engine went. I wasn't 100% happy today, I think we still need to get a little bit quicker. The McLarens and the Mercedes look quick and Ferrari have a decent long run pace, so we'll have to see where we are. This circuit is one of the tougher ones here due to the hot and humid conditions."
"It was the engine (Mark stopped early in the second session). You never want your Friday disturbed and today's problem cost us quite a bit of track time, but the car felt pretty good in the quick stuff and also at low speeds. It's never ideal to lose an engine, but we did, although it was quite high mileage. It's good that Vettel's up there, but it's where we expected to be, it would have been nice to feel the option tyres today, but we'll have to do that tomorrow."
-source: red bull