Reigning MotoGP World Champion Valentino Rossi made a fast start to the Turkish Grand Prix - setting the third fastest lap time in first free practice - but then went backwards during this afternoon's second session to end the day down in eleventh.

"This morning we were fast straight away and this was quite encouraging," confirmed the Camel Yamaha rider. "We were third and we thought that we would be able to continue in this way during the afternoon. However we made some modifications in order to improve the acceleration and unfortunately we lost a lot of grip in braking. In fact our lap times were more or less the same in the afternoon but the track was about half a second faster - this morning it was quite dirty - and now we are in 11th place.

"I am a bit worried but also quite positive because we made some changes at the end of the session, back towards this morning's settings, and we improved a lot and set our fastest lap of the day. So far we don't have any vibration (chatter) and so we hope that it won't appear tomorrow if the grip improves," added the Italian superstar, who was just over one second from fastest man Nicky Hayden.

As a sign of his second session troubles, Rossi was comfortably outpaced by team-mate Colin Edwards - who was sixth fastest in both practice sessions and improved his lap time by 1.4 seconds in the afternoon.

"We started out with the base setting from Qatar but it didn't work very well for us here. Basically we then decided to go with a newer front tyre than the one we've been using in testing and it went much better," revealed the Texan , who lapped 0.6secs faster than Rossi today. "Combined with a few tweaks to the suspension I built up my confidence in the front and I was able to lay down some good lap times.

"In the end we put a pretty consistent run together and I'm happy. We're still getting some vibrations but it's only in a couple of corners and we can work around them with more time on the bike tomorrow; hopefully it will stay dry. The track was really dirty this morning but it started to clean up in the afternoon. If it stays dry then the grip should improve as the weekend goes on, but they're saying it might rain so I guess we'll have to wait and see," he added.

"In the morning things went well for Valentino and in the afternoon they went well for Colin so you could say we had a balanced day!" smiled team director Davide Brivio. "The good news is that we have been able to work as we would on a normal weekend, without the distractions caused by the (chatter) problems we experienced in the first race.

"We collected a lot of good information today that we can put to use tomorrow and find a way forward with the set-up of the bikes. The only question mark is the rain so the only thing we ask for is at least a few dry laps so that we can evaluate the solutions we come up with tonight. Valentino lost his feeling a little bit this afternoon but we will compare the data from the whole day and find the best way to work tomorrow," he concluded.

Final free practice and qualifying will take place on Saturday.