Reigning MotoGP champion Marc Marquez set the pace in the post-Catalunya Grand Prix test at Barcelona, beating Maverick Vinales in the closing minutes.
Other than Ducati, which won on Sunday with Andrea Dovizioso, and the satellite Aspar and Avintia outfits, all the teams stayed on at Barcelona for one day of official in-season testing.
Championship leader Vinales finished a perplexed 10th in the race, as Yamaha struggled, but looked set to bounce back with the fastest time with a 1m44.932s recorded early on Monday afternoon.
Yamaha has a pair of new frames to evaluate during two days of testing this week, having scrapped a plan to run at Aragon on Wednesday to instead remain at Barcelona on Tuesday.
In a shootout inside the final five minutes, Marquez turned a 1m44.340s to move from fifth to first, 0.592 seconds clear of Vinales.
Both riders improved again with, Marquez's 1m44.071s good enough to finish 0.366s faster than his fellow Spaniard.
Tech3 Yamaha rider Jonas Folger finished third ahead of the polesitter for Sunday's race, Dani Pedrosa, albeit both more than nine tenths adrift.
Aleix Espargaro set the fifth-fastest time for Aprilia, ahead of LCR Honda's Cal Crutchlow, Folger's team-mate Johann Zarco, Scott Redding and Tito Rabat.
Valentino Rossi finished 10th with a 1m45.635s, 1.564s slower than Marquez.
Suzuki had three bikes in action, as rookie Alex Rins returned after breaking his left wrist in two places at Austin in April.
Rins set the 17th-fastest time, just ahead of his injury stand-in Sylvain Guintoli and three spots behind regular team-mate Andrea Iannone.
Suzuki will join Yamaha in testing at Barcelona on Tuesday, along with KTM, which is staying until Wednesday but without Bradley Smith due to the finger injury he sustained on Saturday.
MONDAY TESTING TIMES:
|3||Jonas Folger||Tech3 Yamaha||1m44.972s||0.901s||42|
|6||Cal Crutchlow||LCR Honda||1m45.296s||1.225s||60|
|7||Johann Zarco||Tech3 Yamaha||1m45.452s||1.381s||33|
|8||Scott Redding||Pramac Ducati||1m45.565s||1.494s||59|
|9||Tito Rabat||MVDS Honda||1m45.582s||1.511s||59|
|11||Danilo Petrucci||Pramac Ducati||1m45.863s||1.792s||28|
|12||Jack Miller||MVDS Honda||1m45.897s||1.826s||52|