Mexican GP: Testing 2018 parts disrupted Verstappen's Friday

Verstappen completed just 16 laps in the morning at Mexico City, compared to the session-high mark of 42 covered by pacesetter Valtteri Bottas.

He put this lack of mileage down to having to stop running early so the car could be changed back to current specification.

"We tried out some development parts for 2018 and then changed the set-up, so you lose a bit of momentum there already," Verstappen explained.

"And you cannot really set up the car because there are a lot of different parts.

"Going into the second session I was just chasing a bit with the car balance, trying to correct it, because you miss the morning, and then it could have been a bit better.

"I was not happy with how the car was behaving but still we were third so the speed is there."

Verstappen's afternoon session was then curtailed by an engine problem, though he underlined that "it was an old engine so I'm not too worried about it".

His team-mate Daniel Ricciardo ended the day fastest by 0.131 seconds over Lewis Hamilton's Mercedes, but feeling he could have gone quicker.

"It is always nice when you top a session, it always feels good, but we have been chipping away at it," said Ricciardo.

"In the long runs we can still find a bit more pace but on low fuel we are more or less there.

"We know Mercedes have more on Saturday so I think we still have to find a few tenths if we want to stay ahead of them tomorrow, but not a bad Friday."

Ricciardo headed a top six covered by less than half a second in the afternoon, as Red Bull, Mercedes and Ferrari appeared evenly matched on single-lap pace.

"I think it is always going to be pretty close between the top three teams now for these last few races," Ricciardo added.