The all-new machine's potential is currently being limited by its engine performance, prompting Pedrosa to skip the recent Sepang test while awaiting developments from HRC.

Those developments duly appeared on Tuesday and the 22-year-old, whose only previous appearance on the '08 was immediately after the Valencian season finale, was quickly up to speed at his home circuit.

Pedrosa concluded the opening day of the three-day test with the second fastest time - just 0.134secs behind world champion Casey Stoner - and having lapped almost 0.7secs inside his fastest lap during the Spanish Grand Prix in March.

"We've been testing with the new bike exclusively today and we were looking to see if the issues we had at the first test in Valencia have been solved. The electronic engine settings which control the power delivery and the engine braking have been improved which makes the machine more rideable and quicker too," revealed the 2007 MotoGP World Championship runner-up. "The feeling from the chassis is quite good but I have to continue working on the settings to suit me.

"In Valencia the bike wasn't ready to complete a lot of laps but today we have been able to do many more," continued the Spaniard, who completed 60 laps. "There has been progress in some areas and in other areas we still have some work to do. We've tried some changes with the chassis today and we'll look for further improvements tomorrow. So far we haven't tested any new tyres and this is an important area to improve lap times, so I'm confident we can make further progress throughout this test."

Team-mate Hayden was back on board the RC212V just ten days after the Sepang test and he too was encouraged by the latest developments - although they provided no miracle cure. The 2006 World Champion completed 63 laps and finished the day with the fifth fastest time, half a second behind Pedrosa.

"Overall it was a pretty positive day," declared the American. "We tried some modifications to the engine to get it running better than it did at the previous two tests and now it seems to be more responsive and to be running a little better - though it's still not quite there.

"We also changed a few things on the chassis, for instance the offset, which took a while and reduced our track time somewhat, but this was important to try to understand more about the machine. This is the first time I've been able to come into the garage, focus on the 2008 machine and spend the whole day on it so that was beneficial.

"It wasn't a perfect start to the test - that's pretty rare - but we definitely learned some useful things and I'm encouraged by the start we've made here today. Let's see what happens over the next few days and aim to make some more improvements," he concluded.