By Alan Baldwin
(Reuters) - AlphaTauri's Pierre Gasly was surprisingly fastest in final practice for the Azerbaijan Grand Prix on Saturday, as Red Bull's Formula One championship leader Max Verstappen crashed into the barriers.
Frenchman Gasly, a winner for the Red Bull-owned team in Italy last season, lapped the Baku street circuit with a best time of one minute 42.251 seconds in an eventful session on a hot afternoon.
Verstappen's team mate Sergio Perez was second quickest, 0.344 slower.
Mercedes' seven times world champion Lewis Hamilton was third, after earlier complaining of a lack of grip, but his pace was increased significantly by running in the Mexican's slipstream.
The aerodynamic 'tow' on the long and fast straight may have been worth as much as six tenths of a second to the Briton, Mercedes estimated.
The champions have struggled for speed in every session and were out of the top 10 on Friday. Hamilton's Finnish team mate Valtteri Bottas was only 13th and 1.494 off Gasly's time.
Verstappen, leading the championship for the first time and four points clear of Hamilton after five races, was left as a mere spectator for much of the session after going into the barrier at turn 15.
The session was halted for the car, with a broken front wing and suspension, to be removed.
Ferrari's Charles Leclerc, who also hit the barriers at the same place on Friday, was fourth fastest with team mate Carlos Sainz fifth and McLaren's Lando Norris sixth.
Perez, who was fastest on Friday and has a strong record in Baku with two previous podium finishes for now-defunct Force India, was top of the timesheets until near the end when Gasly pulled out his best effort.
Williams' George Russell brought out the virtual safety car when he stopped with an engine problem.
"No power. No gears. Lost power," said the Briton over the team radio.
(Reporting by Alan Baldwin in London; Editing by Hugh Lawson)