World champion Jorge Lorenzo was fastest in Saturday's rain-hit testing at Jerez in Spain, the final weekend session before the season-opening MotoGP in Qatar on April 7.
Yamaha rider Lorenzo was more than a second quicker than Honda duo, Dani Pedrosa and Marc Marquez after completing 39 laps on the first day of the three-day session where riders struggled with the overcast conditions and water-logged track.
"We stayed on the track the whole day in the wet conditions and it was good to see how the bike performed," said Lorenzo, who clocked 1min 47.423sec.
"We are quite good in the wet here in Jerez. It's the first time we are in these conditions so it's important to understand what our levels are. It's important to be competitive in this situation."
Teammate Valentino Rossi was sixth fastest with a best lap of 1min 49.443sec.
"The conditions today were very bad so we had to work on the wet," said the former world champion Italian, who put in 36 laps.
"The feeling with the bike was not so bad but we had some problems with the life of the tyre, after some laps we started to spin a lot. It will be hard in a wet race to do 27 laps in a row.
"We also have an issue with the quantity of wet tyres as we have only two today, we have four in total so we keep two for tomorrow but we hope tomorrow will be dry."
1. Jorge Lorenzo (ESP/Yamaha) 1min 47.423sec, 2. Dani Pedrosa (ESP/Honda) at 1.051, 3. Marc Marquez (ESP/Honda) 1.101, 4. Andrea Iannone (ITA/Ducati Pramac) 1.561, 5. Michele Pirro (ITA/Ducati) 1.869, 6. Valentino Rossi (ITA/Yamaha) 2.020, 7. Nicky Hayden (USA/Ducati) 2.220, 8. Cal Crutchlow (GBR/Yamaha Tech3) 2.269, 9. Stefan Bradl (GER/Honda LCR) 2.367, 10. Andrea Dovizioso (ITA/Ducati) 2.843