This morning it was Troy Bayliss, this afternoon Troy Corser.
Corser, armed with his factory Yamaha R1, shot to the top of qualifying for Sunday's two World Superbike races at the new Portimao circuit in Portugal, the Aussie lapping at 1:55.55.791 to take the top spot while his countryman Bayliss dropped to 10th overall.
Brit Leon Haslam maintained his speed, the HM Plant Honda rider jumping up to second in Friday's qualifying session, some 1.4 seconds off Corser's best and a few tenths better than Ducati Xerox's Michel Fabrizio.
Sterilgarda Go Eleven's Ruben Xaus improved from 10th in the morning session to fourth in the afternoon to fill the provisional front row for Sunday's races.
Haslam's teammate Cal Crutchlow dropped from second this morning to fifth this afternoon, with fellow Honda riders Chris Walker, Jonathan Rea and Carlos Checa ending up sixth, seventh and eighth, respectively.
Then came Kawasaki's Regis Laconi and finally Bayliss in 10th, the Aussie's best a 2:00.012 - off his 1:59.492 set in the morning session.
1. Troy Corser (Yamaha) 1:55.791
2. Leon Haslam (Honda) 1:57.214
3. Michel Fabrizio (Ducati) 1:57.440
4. Ruben Xaus (Ducati) 1:58.115
5. Cal Crutchlow (Honda) 1:58.327
6. Chris Walker (Honda) 1:58.557
7. Jonathan Rea (Honda) 1:59.356
8. Carlos Checa (Honda) 1:59.676
9. Regis Laconi (Kawasaki) 1:59.939
10. Troy Bayliss (Ducati) 2:00.012