Movistar Honda rider Marco Melandri was fastest in practice for Sunday's inaugural Turkish MotoGP.
The Italian, one of four riders chasing second place in the standings behind champion Valentino Rossi, came home ahead of team-mate Sete Gibernau.
Melandri's fastest time was one minute 53.506 secs, with Repsol Honda rider Nicky Hayden in third place.
Kawasaki's Shinya Nakano came fourth with Rossi, seeking a record-equalling 12th win of the season, in fifth.
Rossi's team-mate Colin Edwards, who is fighting Hayden, Melandri and Max Biaggi for the runner-up spot, finished seventh.
Biaggi was 10th while Briton James Ellison, looking for a third consecutive points finish on the Blata-WCM, came home in 18th place.
Friday's practice times:
1 Marco Melandri (It) Honda 1:53.506
2 Sete Gibernau (Sp) Honda 1:53.945
3 Nicky Hayden (US) Honda 1:54.774
4 Shinya Nakano (Jpn) Kawasaki 1:55.015
5 Valentino Rossi (It) Yamaha 1:55.078
6 Carlos Checa (Sp) Ducati 1:55.171
7 Colin Edwards (US) Yamaha 1:55.171
8 Toni Elias (Sp) Yamaha 1:55.208
9 John Hopkins (US) Suzuki 1:55.292
10 Max Biaggi (It) Honda 1:55.478