The opening day of practice for the Portuguese MotoGP at Estoril once again highlighted the contrast in competiveness of the Ducati GP12 depending on wet and dry conditions.

In the damp morning session, factory team-mate Nicky Hayden and Valentino Rossi were second and third quickest behind Yamaha's Ben Spies.

Yet when the track dried further for the afternoon, the pair slipped down to seventh (Hayden) and ninth (Rossi), with satellite Ducati rider Hector Barbera in-between.

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Still, Hayden's 0.6sec time difference to Honda's pace setter Casey Stoner was an encouraging margin.

"Conditions weren't perfect this morning, but since they were calling for a good chance of rain in the afternoon, we thought it was worth having a look toward the end," said Hayden, who qualified on the front row last weekend in Jerez.

"The track was patchy, but I've got to say that Bridgestone's new tyre is much better and safer in those conditions.

"This afternoon, the track was completely dry except for water seeping up in the last corner, which made it tough to see the line. We made a couple of gains during the session, but I felt like the time went by really quickly.

"We've still got a lot of work to do, especially in the side-to-side sections, where I'm having some difficulty changing direction. Hopefully we can do a good job with the data tonight and be more consistent tomorrow."

Rossi is continuing work with his new 'Ducati-style' set-up, very similar to that used by Hayden. The seven time MotoGP champion was pleased with his braking and corner speed, but needs to find time in the final sector.

"We had a decent start to the weekend because I was able to ride the bike pretty well, I didn't finish so far from the front in terms of lap times and, most importantly, I was fast in several sections of the track," said Rossi, whose best lap time was 0.961s from Stoner.

"I'm only losing a lot in the last split, T4, so along with the technicians, I'm trying to understand why I'm having such a hard time in the last corner, where there's very limited grip and the back of the bike slides a lot.

"Still, I can brake hard and enter the corners pretty quickly, and if we're able to fix the rear, we can get closer.

"Our goal is to try to be competitive around the entire track. We'll see what the weather is like, because this morning's mixed conditions were difficult, and then they were better in the afternoon.

"Although we went well in the wet, we hope the weather stays nice and that it will be completely dry on Sunday."

Rossi has finished tenth and ninth in the races so far this season.