Casey Stoner picked up where he left off in France by dominating both of Friday's free practice sessions in Catalunya - despite unpredictable weather and after-effects of the 'flu.
Stoner, whose second win from four Repsol Honda starts moved him back up to second in the championship, was leading when a rain shower arrived in FP1 - then rose to the top on a drying track in FP2.
The 2007 world champion was 0.486sec ahead of Marco Simoncelli in FP1, then extended his advantage over the Italian to 0.528sec in the quicker afternoon session.
"We're quite happy with the day, unfortunately we didn't get a lot of good wet or dry track time so a lot of time was wasted in changeable conditions and not achieving much," said Stoner. "However, in general we got a pretty good feeling with the bike and everything seems to be working well.
"We would like to improve rear grip and turning on the exit, also some more stability on the brakes, but in general the bike feels good and we're confident we can go faster tomorrow, hopefully in dry conditions and we'll see what we can do."
Stoner has been suffering from the 'flu since Le Mans and is yet to fully recover.
"Physically I feel better than I have done in the past weeks, I've got blocked sinuses which doesn't help when I'm trying to concentrate and my ears are popping but I'm trying to put this to one side and concentrate on the job at hand," he said.
Stoner's Repsol Honda team-mate Andrea Dovizioso completed an all-Honda top three, with a best lap time 0.663sec from the Australian.
"All in all it was a good session and we tested both soft and hard tyres in preparation for the race, in case there will be changeable weather conditions," said the Italian.
"I'm happy with the feeling with the bike. We are 6 tenths from Casey but I think we can improve tomorrow. We did a good job and we will continue working in this direction tomorrow".
Third Repsol rider Dani Pedrosa is missing the event due to the broken collarbone he sustained in a clash with Simoncelli at Le Mans.