Dani Pedrosa continued his rich vein of form by setting a record-breaking pace during day one of a private test at Aragon, at which title rival Jorge Lorenzo is also present.
Yamaha's Lorenzo leads the standings by a reduced 13-points following Pedrosa's third victory of the season at Brno - and the Repsol Honda rider was a clear 0.488s ahead of Lorenzo by the end of Tuesday's opening day at Aragon.
Pedrosa worked on suspension and electronics as he sought better rear traction and power delivery from his factory RC213V.
The Spaniard completed 35 laps with a best lap time of 1m 47.983s, which compares with the official race lap record of 1m 49.046s and pole record of 1m 48.451s, both set on an 800cc Honda by Pedrosa's injured team-mate Casey Stoner.
"In the morning we did some laps to get back into the rhythm and remember the lines on this track, then in the afternoon we really started to work on the bike set up,” said Pedrosa.
“We worked a lot with the suspension trying to improve the rear grip especially and with the mapping and electronics to make the bike smoother.
“The track conditions will be better tomorrow, so the target is to stick with the same plan, try the same things and see if we can improve a little more with the suspension because the configuration today was not perfect.
“This is the last test of the season, so it's important to take advantage of it for the upcoming races and see if we can get something else from the bike.”
Lorenzo was second fastest on Tuesday, with his team-mate Ben Spies +0.664s from Pedrosa in third.
Then came the LCR Honda of Stefan Bradl (+1.587s) followed by the second Repsol machine of Jonathan Rea (+2.696s), standing in for Stoner, who completed the five rider line-up.
The Aragon test concludes on Wednesday evening. Ducati is holding private test at Mugello this week.