The Mercedes pair of Lewis Hamilton and Nico Rosberg topped the timesheets on Friday in first practice for the United States Grand Prix.

But engine trouble cut short Daniel Ricciardo’s morning, leaving the Australian in 17th place ahead of the afternoon session.

Red Bull teammate and reigning world champion Sebastian Vettel was seventh but he’s going to start from the pit lane on Sunday and will likely skip qualifying on Saturday.

World championship leader Hamilton posted the fastest lap around the 5.513km Circuit of the Americas in 1 minute 39.941 seconds, with teammate Rosberg 0.292 seconds behind.

Hamilton has won past four races and leads Rosberg by 17 points in the standings while Mercedes have already secured the constructors’ title.

McLaren’s Jenson Button was third, Daniil Kyvat of Toro Rosso fourth, while another McLaren driver, Kevin Magnussen, took fifth.

Vettel will start from the pit lane as penalty for a total power unit change.

Such a scenario had been on the cards as a consequence of his technical woes at the start of the season which have now come back to haunt him.

With the new 1.6-litre turbo-charged power unit comprising six components, under the regulations a sixth change of one of those leads to an automatic grid penalty.

But with Vettel to the limit on most of the components, Red Bull have decided for a complete change of the system, resulting in a pit-lane start.

In order to conserve the new power unit, it is now likely the outgoing four-times champion will sit out qualifying on Saturday.

Speaking on Wednesday, and expressing his frustration at the rules which means the fans will be denied his presence on track throughout qualifying, Vettel said: “I didn’t make them, but equally everyone has to respect them, and they are pretty clear.

“So instead of burning mileage in qualifying, which you would regret later on in Brazil or Abu Dhabi where you might not see the finish line, you skip it.”

There are only nine teams present in the US as Caterham and Marussia are skipping the Grand Prix due to financial problems.