Pecco Bagnaia is at huge risk of losing his MotoGP world championship lead at Mandalika after only qualifying 13th for the Indonesian Grand Prix and sprint race, knocked out of a Q2 spot by his own Ducati team-mate Enea Bastianini.
The only consolation for Bagnaia is that it wasn't a flawless qualifying for his title rival Jorge Martin either, as the Pramac Ducati rider - now just three points behind Bagnaia in the standings - crashed in Q2 and couldn't do better than sixth afterwards.
Luca Marini came through from Q1 to take a sensational pole for VR46 Ducati ahead of the works Aprilias, despite still being in a lot of discomfort from the collarbone injury he sustained in India last month.
Bagnaia had consigned himself to Q1 with an error on his best lap on Friday afternoon, and never looked like he'd freeze through to the pole session.
He was only third behind Johann Zarco and Franco Morbidelli after the initial Q1 runs, and though he then went fastest on his next attempt it was not a totally smooth lap - running slightly wide onto the kerbs in sector two costing him momentum.
Marini then beat Bagnaia's time by two and a half tenths of a second, and as the champion failed to improve on his next lap his team-mate Bastianini - returning this weekend after a six-week absence following his Barcelona start crash - outpaced Bagnaia by 0.099s to take second in Q1 and deny the points leader a Q2 place, leaving him 13th on the grid for both races. Team manager Davide Tardozzi told MotoGP's broadcast that Bagnaia had lacked confidence in the final braking phase.
That gave Martin a clear shot going into Q2, but he ran wide onto the kerbs and fell going into the long Turn 16 right-hander early on - moments after outside title contender Marco Bezzecchi had had pretty much the same accident.
Martin tripped on his own bike as he began his hurry back to the pits, then had to use a hard front tyre on his spare Ducati.
He got up to a provisional fourth then couldn't improve on that time, relinquished his last lap trying to allow Marc Marquez ahead as the Honda rider chased him for a tow, and had to settle for an outside row two spot.
Aprilia had looked set for a 1-2 for most of Q2 before a brilliant 1m29.978s lap by Marini pushed Maverick Vinales and Aleix Espargaro to second and third.
Fabio Quartararo gave Yamaha a rare second-row start in fourth ahead of Brad Binder's KTM and Martin.
Bezzecchi, who seemed unlikely to be in Indonesia when he broke his collarbone last weekend in training, had the same hard tyre limitation as Martin and qualified on the outside of row three in ninth behind Fabio Di Giannantonio and Marc Marquez.
Outgoing rider Di Giannantonio represents Gresini alone for the races after team-mate Alex Marquez withdrew following Friday practice due to ongoing pain from the ribs he broke in India last month.
Bastianini and RNF Aprilia's Miguel Oliveira complete the top 12.
Early Q1 pacesetters Zarco and Morbidelli slipped back to 14th and 15th on the grid, Zarco ending his session with a high-speed low-side into the gravel at the quick Turn 11 right-hander.
The three non-Marquez Hondas bring up the rear of the grid, with LCR's long-time injury absentee Alex Rins slowest but at least continuing with this weekend at present after his aborted Japanese GP return.
