Jorge Lorenzo edged ahead of Andrea Iannone to top MotoGP FP2 at Catalunya, as a crash for Marc Marquez leaves him outside of the provisional Q2 places.
FP1 pacesetter Valentino Rossi set the initial benchmark on his factory Yamaha with a 1:41.133s, though was soon pipped by Lorezno with a 1:40.924s.
The Ducati rider and his future Honda stablemate Marquez debated top spot for the next handful of laps, with Lorenzo usurping a 1:40.758s from Marquez with a 1:40.512s.
Lorenzo extended his advantage with a 1:40.165s, and raised his pace again to a 1:39.817s after Marquez demoted him with a 1:39.990s.
In the closing stages, as the rest of the field pushed to secure a place inside the top 10 should conditions not allow overall improvements on Saturday morning, Yamaha's Maverick Vinales was the first big improver with a 1:38.652s.
The Spaniard's time at the top lasted only briefly, however, as Lorenzo produced a 1:38.930s to go half a second clear of LCR Honda's Cal Crutchlow.
Marquez opted against fitting fresh slicks and remained on the same hard front tyre he ran for the entire session.
This proved detrimental to his hopes of bagging a provisional Q2 slot, as he crashed going through Turn 4 just seconds after Lorenzo shot to the top of the pile again.
Marquez's demise saw him slip to 12th on the timesheets, while Suzuki's Iannone leaped up the order to second and to within 0.107 seconds of Lorenzo's best.
Vinales slotted into third, while last year's Catalan Grand Prix winner Andrea Dovizioso headed Crutchlow in fourth.
Dovizioso's future factory Ducati team-mate Danilo Petrucci lifted himself from 19th in FP1 to sixth in the afternoon, with Johann Zarco on the Tech3 Yamaha, the sister factory Honda of Dani Pedrosa, Hafizh Syahrin on the second Tech3 bike and Avintia's Tito Rabat completed the top 10.
However, Rabat ends the day 11th overall, as Rossi's 1:39.456s from FP1 kept him fifth on the combined times, while his 1:39.989s in the second session was only good enough for 11th.
Wilcard Mika Kallio was comfortably to KTM runner in 13th, while Sylvain Guintol ended the day 25th on his Suzuki.
The Frenchman's team-mate Alex Rins was a late faller and was left in 16th as a result. Aprilia's Scott Redding fell at Turn 10 moments later.
Marc VDS' Franco Morbidelli added a second tumble to his Friday scorecard, while Pol Espargaro threw his KTM into the scenery of Turn 5 the latter stages.
