Colin Edwards was content to start the season ending grand prix at Valencia with the ninth fastest Friday lap time in the wet conditions, but team-mate James Toseland struggled.
Sixth in the rain-lashed morning session, weight distribution changes to Edwards' YZR-M1 machine helped him climb as high as fourth under grey and gloomy skies in the afternoon, although he had dropped to 1.5sec behind pace setting countryman Nicky Hayden by the end of the hour.
"We started with the rain setting I used to back at Donington Park and it felt fine, but it uses quite a lot of weight on the front. So we tweaked it to get some more weight on the rear tyre and I felt pretty good," Edwards explained.
"I'm going to try and make some more changes with the team overnight to get a bit more weight on the rear to see if we can just to get a bit more confidence. This track in the rain is really tough and conditions were quite difficult. It is a weird feeling because you can't really push like you can in wet conditions on other tracks.
"Normally you can get the front and the rear moving and you're feeling for grip, but here it is all or nothing. You can't spin the rear and feel what its doing on this track. You've either got grip or you haven't and you don't get a lot of warning when there is no grip as we saw with a few guys crashing out. There is still a lot to fight for on Sunday so I'm reasonably happy with progress today," added the Texan, who is ten points behind sixth-placed Hayden in the championship standings.
Toseland has prior experience of Valencia on a WSBK machine, but the Briton struggled to find a set-up on his MotoGP debut and was left 1.4sec behind his team-mate.
"It was a tough day and we've got to find something to improve because the forecasts are for more rain tomorrow, and I need to find a bit more from the bike," confessed Toseland, who will finish the season third out of the four MotoGP rookies whatever happens on Sunday.
"I just didn't have a very good feeling and I'm not happy, but I've got some ideas. In those greasy conditions I just haven't got enough feel from the rear and we need to find a lot more contact with the rear tyre. It feels a bit like riding around on eggshells at the moment.
"This track is always tricky in the wet. When it is heavy rain, everybody has a respect for the place because they know how easy it is to get caught out. But when it is drying out, it doesn't give more grip, even though there is less water on the surface. People get sucked into thinking they can go faster and you don't get any warning before you get a big slide.
"This wasn't the start I wanted with tenth place in the championship to battle for on Sunday, but I'm confident we can make some big improvements," concluded JT, presently eleventh in the standings and eleven points behind Loris Capirossi, who was 17th on Friday.