MotoGP championship leader Pedro Acosta led the way in the first premier-class session of the returning Brazilian Grand Prix at Goiania.

Heavy rain - a persistent feature already in the build-up to the race weekend - forced a delay to the day's itinerary, meaning MotoGP's opening practice (extended by 15 minutes for Goiania layout acclimatisation) ran an hour later than scheduled.

A wet track met the premier-class riders, and though it dried gradually through the session, rain is expected to return before MotoGP resumes practice later on Friday.

It was a largely-incident free session, excluding an off-track excursion here and there.

Pramac Yamaha rider Jack Miller was the first to try slicks, under half an hour into the running, but he'd completed a full 10-lap run - navigating his way around the wet patches - before anyone joined him in swapping over from the wet rubber.

But the wet-tyre runners were still fastest until the final minutes of the session, when Miller suddenly challenged for the top of the timesheets - coming up 0.087s short.

Marc Marquez had led when the chequered flag flew but Acosta, Miller and Marco Bezzecchi all jumped ahead in the final moments.

Injury returnee Fermin Aldeguer, moving around the paddock with a crutch, was a credible eighth in his first session back, 0.888s off the pace, with 15 laps in the books (joint-fewest with home hero Diogo Moreira).

Results

1 Pedro Acosta (KTM) 1m26.688s
2 Jack Miller (Pramac Yamaha) +0.087s
3 Marco Bezzecchi (Aprilia) +0.230s
4 Marc Marquez (Ducati) +0.287s
5 Franco Morbidelli (VR46 Ducati) +0.482s
6 Maverick Vinales (Tech3 KTM) +0.818s
7 Jorge Martin (Aprilia) +0.858s
8 Fermin Aldeguer (Gresini Ducati) +0.888s
9 Pecco Bagnaia (Ducati) +0.891s
10 Alex Marquez (Gresini Ducati) +0.977s
11 Enea Bastianini (Tech3 KTM) +1.016s
12 Fabio Di Giannantonio (VR46 Ducati) +1.046s
13 Brad Binder (KTM) +1.107s
14 Alex Rins (Yamaha) +1.260s
15 Johann Zarco (LCR Honda) +1.369s
16 Toprak Razgatlioglu (Pramac Yamaha) +1.580s
17 Ai Ogura (Trackhouse Aprilia) +1.912s
18 Diogo Moreira (LCR Honda) +1.990s
19 Joan Mir (Honda) +2.177s
20 Luca Marini (Honda) +2.238s
21 Raul Fernandez (Trackhouse Aprilia) +2.264s
22 Fabio Quartararo (Yamaha) +2.810s