Sepang - Maverick Vinales was the fastest rider on day two of the 2018 test at Malaysia's Sepang circuit Monday, with his Yamaha team-mate Valentino Rossi and Cal Crutchlow of rival Honda close behind.
Looking comfortable on his new bike, Spain's Vinales logged 1 minute 59.355 seconds - 0.035 seconds faster than Rossi, a nine-times world champion.
Both the Yamaha riders worked on improving the power of their new Yamaha engines, body positioning and extending tyre life.
"Today, it was a competitive day. The fight (in the 2018 MotoGP race) is going to be tight," Rossi said.
"The new fairings are good. The front tyre now has more contact with the track," he told reporters.
Last season Rossi and Vinales struggled with Yamaha's 2017 chassis, poor rear tyre grip and rapid tyre degradation.
Rossi, 38, is the oldest rider in the MotoGP race. There is much speculation about whether he will race in the 2019 season - a question he says he will answer after this year's season begins.
There was a moment of drama on the circuit when Suzuki's Andrea Iannone was forced to stop on track with his bike spitting flames.
Testing began with damp patches on the track after overnight rain but conditions became scorching hot later in the day.
British rider Crutchlow said he was happy with his bike and was concentrating on its set-up.
Spain's Marc Marquez, a four-time MotoGP champion, came in seventh, 0.347seconds off the pace, while his team-mate and countryman Dani Pedrosa, was 12th in 1min.59.999 seconds.
Spaniard Jorge Lorenzo, a three time MotoGP champion, registered 1.59.498 seconds on his Ducati to take fourth. His team-mate Andrea Dovizioso finished eighth - 0.377 seconds slower than Vinales.
Australia's Jack Miller who was fifth logged 1min 59.509 seconds on a Ducati. Frenchman Johann Zarco, in his second year in the top class on a Yamaha, finished sixth quickest with a time of 1min 59.702.
Ducati's Danilo Petrucci of Italy was ninth at 1min 59.747sec, Suzuki's Andrea Iannone came in 10th with a time of 1.59.917sec and Spain's Aleix Espargaro on an Aprilia finished 11th - 0.570sec off the pace.
Honda MotoGP rider Dani Pedrosa was quickest on Sunday, the first day of testing. Dovizioso was second fastest and Lorenzo came in third. The testing ends Tuesday.