Red Bull's Max Verstappen and Daniel Ricciardo finished first and second in the first practice ahead of Sunday's Azerbaijan, in a scorching session that was halted with a red flag after Sergio Perez of Force India crashed into the barriers.
Verstappen, using Supersoft tyres, was the session's fastest with a time of 1:44.410, with teammate Ricciardo  who collided with Perez during practice in 2016  four tenths behind.
Championship leader Sebastian Vettel on the Soft compound tyre finished third on 1:44.967, with Mercedes duo Lewis Hamilton and Valtteri Bottas in fifth and sixth respectively behind Perez in fourth.
The Force India driver was one of the more impressive drivers in Baku last year, and had been flying through the city circuit before his collision late on.
He escaped unscathed after crashing against the external wall at a narrow section at Turn Eight, although his car lost its rear right wheel and Force India mechanics may struggle to get him back on the track before the second practice session on Friday afternoon.
Eighteen of 22 cars finished the challenging anti-clockwise track last year, despite driver complaints about safety, although there were signs during practice that the narrow, winding circuit will cause some trouble during Sunday's race.
On several occasions, drivers struggled to make corners and bailed down escape roads, with Bottas, who hit a Formula One record top speed of 373kmh last year, going into a spin at Turn 10, the same spot where Hamilton clipped the barriers in 2016.
Force India's Esteban Ocon finished seventh, ahead of Williams' Felipe Massa, Ferrari's Kimi Raikkonen and Daniil Kvyat of Toro Rosso.
Sauber pair Pascal Wehrlein and Marcus Ericsson, whose preparations have been overshadowed by the departure of team principal Monisha Kaltenborn, finished at the bottom of the standings