Yamaha has completed two days of private testing at Sepang, bringing an end to this year's MotoGP on-track action.
Factory pair Valentino Rossi and Maverick Vinales were joined by Tech3 satellite rider Johann Zarco, who also worked closely with the factory Yamaha outfit in Valencia testing earlier this month.
None of the three were present at last week's combined Jerez test, with Honda riders Marc Marquez and Dani Pedrosa also skipping it in order to save their allocation of test days.
While Yamaha has not issued any official comment on the test, it is understood that the main focus of Monday and Tuesday's running was on defining the final engine specification for the 2018 M1.
"In Sepang we focused on testing different engines, and once we have decided on the spec we will work on the new chassis, but that won't be until the [Sepang] January test," a Yamaha source told Autosport.
Both Rossi and Vinales had four different varieties of bike at their disposal in Sepang, having sampled a mixture of 2016 and '17 chassis in Valencia, while Zarco had two different specs to try.
The trio were also able to get some wet mileage under their belts on Monday.
Official pre-season testing resumes on January 28 at Sepang, which comes at the end of a two-month winter testing ban.