Factory Ducati rider Francesco Bagnaia set the pace in second MotoGP practice at the Barcelona Grand Prix, as championship leader Jorge Martin ended up fifth.
A late flying lap from Bagnaia on the GP24 propelled Bagnaia to the top of the order with a 1m38.918s, just under a tenth quicker than VR46 rival Marco Bezzecchi.
Bezzecchi had led the majority of the session on last year's GP23 bike, immediately improving on Takaaki Nakagami's FP1 benchmark with a 1m40.242s when the hour-long session began at 3pm local time.
The Italian then became the first rider to break the 1m40s barrier, stamping his authority with a 1m39.829s.
Both Gresini's Alex Marquez and Tech3 GasGas rider Pedro Acosta were also able to lap in the 1m39s bracket early in the session, but their laps were more than a tenth-and-a-half slower than Bezzecchi's best effort.
Aprilia's Vinales joined the '1m39s club' after the halfway point of the session, but he too couldn't lap within a tenth of Bezzecchi.
It wasn't until 13 minutes left on the clock that the Italian was dislodged from the top, with Martin posting a 1m39.652s on a fresh set of soft tyres to hit the front.
The Pramac rider then shaved another three tenths on his next flying lap, getting down to a 1m39.214s on his Ducati GP24.
LCR's Johan Zarco then enjoyed a brief stint at the front, taking advantage of a slipstream from a number of Ducati bikes in the final sector to shoot to the top with a 1m39.197s.
However, it was beaten by a flurry of laps right at the death of the session, as riders made a final attempt to secure an automatic entry into Q2.
It was early pacesetter Bezzecchi who was the first big improver, moving the goalposts with a 1m38.998s.
But Bagnaia was able to edge him out in the final moments of the session to end Friday practice on top, as he seeks to defend his crown against Martin in this weekend's finale.
The retiring Aleix Espargaro again displayed his Barcelona prowess with the third-fastest time of the day on the Aprilia, ending just over a tenth down on Bagnaia's chart-topping effort.
Zarco managed to hang on to fourth place to secure a morale-boosting Q2 spot for Honda, while Martin had to settle for fifth place, 0.296s behind his title rival Bagnaia.
Vinales complimented the efforts of team-mate Espargaro in sixth ahead of the Gresini duo, with younger Alex Marquez edging out his brother Marc to grab seventh position.
The final automatic spots in Q2 went to Tech3 GasGas' Pedro Acosta and factory Ducati rider Enea Bastianini, the latter barely hanging on to 10th ahead of the KTM of Brad Binder.
Binder was closely followed by his team-mate Jack Miller, the two KTM riders separated by just 0.001s at the end of the session.
Nakagami was classified 12th, meaning two Honda riders finished ahead of the top Yamaha of Fabio Quartararo in 13th.
Alex Rins behind right behind Quartararo in 14th place on the sister Yamaha M1, while Franco Morbidelli had a torrid session on the Pramac Ducati en route to 15th after an early crash.
| 1 | 1 |  |
Ducati | 24 | 145.757 | ||
| 2 | 72 |  |
Ducati | 26 | 0.080 | 145.639 | |
| 3 | 41 |  |
Aprilia | 22 | 0.027 | 145.599 | |
| 4 | 5 |  |
Honda | 24 | 0.172 | 145.347 | |
| 5 | 89 |  |
Ducati | 25 | 0.017 | 145.322 | |
| 6 | 12 |  |
Aprilia | 24 | 0.010 | 145.307 | |
| 7 | 73 |  |
Ducati | 25 | 0.071 | 145.203 | |
| 8 | 93 |  |
Ducati | 22 | 0.066 | 145.107 | |
| 9 | 31 |  |
KTM | 24 | 0.057 | 145.024 | |
| 10 | 23 |  |
Ducati | 23 | 0.049 | 144.952 | |
| 11 | 33 |  |
KTM | 24 | 0.020 | 144.923 | |
| 12 | 43 |  |
KTM | 24 | 0.001 | 144.922 | |
| 13 | 30 |  |
Honda | 22 | 0.268 | 144.532 | |
| 14 | 20 |  |
Yamaha | 26 | 0.035 | 144.481 | |
| 15 | 42 |  |
Yamaha | 23 | 0.003 | 144.477 | |
| 16 | 21 |  |
Ducati | 20 | 0.016 | 144.454 | |
| 17 | 10 |  |
Honda | 23 | 0.184 | 144.188 | |
| 18 | 36 | |
Honda | 23 | 0.131 | 144.000 | |
| 19 | 25 |  |
Aprilia | 22 | 0.014 | 143.979 | |
| 20 | 88 |  |
Aprilia | 23 | 0.265 | 143.599 | |
| 21 | 37 |  |
KTM | 22 | 0.231 | 143.270 | |
| 22 | 51 |  |
Ducati | 22 | 0.151 | 143.055 | |
| 23 | 6 | Honda | 26 | 0.242 | 142.712 |
