Noriyuki Haga has drawn first blood in his battle with Ben Spies ahead of their World Superbike title showdown in Portimao this weekend, the Japanese rider going faster than his rival by two tenths of a second in free practice.
Spies had been the initial pace setter, lowering his best lap time to 1min 45.118secs by the half way point, but while that was enough to command a sizeable advantage over his rivals at the time, a failure to improve again would see him slip to seventh.
By contrast, Haga languished in the middle of the top ten for the early part of the session, before becoming the first rider to dip below 1min 45secs with an effort of 1min 44.934secs with around 15 minutes of the session remaining.
Even so, Haga did not come away with the best time of all, that honour instead going to Ducati counterpart Jakub Smrz, whose late attempt sliced a further tenth off Haga's lap to leave the Guandalini rider as the surprise early pace setter.
A close session for all the top runners, just three tenths covered Smrz down to Jonathan Rea in ninth position, although some interesting faces filled the positions between.
Most notable of these was Yukio Kagayama in third and Broc Parkes in fourth, both riders kicking off the final events with their respective Suzuki Alstare and Kawasaki teams by setting the third and fourth fastest times.
Leon Haslam, also making his final appearance with the Stiggy Racing team this weekend, was sixth fastest to be the best of the Hondas, marginally ahead of Carlos Checa and Spies.
Michel Fabrizio and Rea followed in eighth and ninth, while Fonsi Nieto and Shane Byrne made it a good start to the weekend for the satellite Ducati contenders in tenth and eleventh respectively.
Elsewhere, BMW and Aprilia – the only manufacturers not to have a top ten representative – were 12th and 13th fastest with Troy Corser and Max Biaggi, while Leon Camier was four tenths adrift of his RSV-4 counterpart in 17th position as he got to grips with the undulating Portuguese circuit for the first time.
Further back, World Superbike debutant Sylvain Guintoli got off to a steady start on the Suzuki Alstare, setting the 22nd fastest time, just over two seconds adrift of the leaders.