Mercedes have confirmed that a 'big-end bearing failure' was the cause of Lewis Hamilton's retirement at last week's Malaysian GP.
The reigning world champion was leading the race at the Sepang International Circuit but he was forced to retire with just 16 laps remaining, handing race victory to Red Bull's Daniel Ricciardo, while team-mate and title rival Nico Rosberg was able to open up a 23-point gap in this year's world championship race.
Mercedes have now confirmed that a bearing failure was the reason why Hamilton's engine failed in Kuala Lumpur, while they also revealed that the Brit will revert to the unit he used at last month's Singapore Grand Prix for this weekend’s race in Japan.
"Our analysis has shown that Lewis' engine suffered a big-end bearing failure," said Mercedes. "This happened without warning after 618km and was preceded by a loss of oil pressure in Turn 15.
"For this race weekend, Lewis will revert to his Singapore unit and Nico will use his Malaysia engine."
The German team's technical director Paddy Lowe concedes the timing of Hamilton's engine failure, with just five races left in the season, was not ideal, but he insists parity remains between the Brit and Rosberg.
"As it stands, despite the failure of this engine, Lewis now has the same stock of power units as Nico for the remaining five races - including used power units which he can fit for free practice sessions," Lowe said. "So, hopefully there will be no further impact to his programme."