Alex Marquez led his brother Marc in the opening MotoGP practice session at Jerez.
The elder Marquez set no laptime at all in the first 20 minutes of the 45-minute session, seemingly battling technical issues on both of his Ducati Desmosedicis - but he went to the top of the timing screens almost immediately after these were resolved.
And he stayed top until the closing minutes when Alex, having crashed at Turn 1 and sprinted back to the pits, rejoined the session on a new soft front and medium rear and lowered the benchmark considerably, to a 1m36.831s.
Several other riders used fresh tyres in the late-session running but none broke into the top five much less the 1m36s range, so the Marquez 1-2 went undisturbed.
There was 0.357s between them at the finish, with the next-fastest rider - Yamaha's Fabio Quartararo - a further two tenths down.
The Qatar Grand Prix pattern of Maverick Vinales being the KTM standout has continued here, Vinales placing fourth with no other KTMs in the top 13.
Joan Mir, whose Lusail weekend was derailed by gastroenteritis, returned to form with fifth place on the Honda.
Honda's returning wildcard Aleix Espargaro was 11th - his programme for the weekend thought to include the testing of a new Honda engine, as riders have complained all season so far about a lack of performance on the straights.
Espargaro's final position was flattered, however, by the use of fresh tyres late on.
Espargaro's fellow testers Augusto Fernandez and Lorenzo Savadori were 17th and 23rd respectively.
