Sergio Perez topped the final free practice session for the Azerbaijan Grand Prix by less than one tenth of a second ahead of Ferrari's Charles Leclerc.
Both Red Bull and Ferrari took turns at ramping up the pace in Baku, with Perez's final lap of 1:43.170 edging Leclerc by seven hundredths of a second, despite having to delay his run due to the stricken Alfa Romeo of Valtteri Bottas, who had an off at Turn 3.
In the final qualifying simulations of the hour, Max Verstappen took third in the second Red Bull, one-quarter of a second off the pace.
Carlos Sainz put the second Ferrari in P4, over a tenth of a second away from Verstappen, and over four tenths off Perez's time.
The two championship-contending teams appeared to be in a class of their own, with the top four over eight tenths of a second ahead of the fifth-placed car.
The final free practice session was delayed by 15 minutes following a crash at Turn 1 in the Formula 2 Sprint, which required a lengthy rebuild of the barriers on the exit of the corner.
The delay will also mean a knock-on effect for the start of the qualifying hour, due to the regulation which requires a minimum two-hour gap between FP3 and qualifying.
Result Free practice 3 - Azerbaijan
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McLaren best of the rest as Mercedes struggle
A strong session for the McLaren team resulted in a fifth and sixth place for the team, with Lando Norris leading Daniel Ricciardo, a driver who is looking for a good performance this weekend.
AlphaTauri's Pierre Gasly took seventh place with a time fractionally slower than the McLarens, whilst George Russell was the highest-placed Mercedes in eighth.
Whilst the high-speed and bumpy nature of the circuit generated porpoising issues for most teams, the problem seemed a particularly violent one for Mercedes, who looked to be bouncing more than other teams.
Russell's Mercedes teammate Lewis Hamilton could only manage 12th, with a time beaten by Aston Martin's Sebastian Vettel and the two Alpines of Fernando Alonso and Esteban Ocon.
It was a relatively clean practice session with minimal incidents. Bottas had the most adventurous hour, with mistakes at Turns 2 and 3 meaning he didn't set a representative lap and finished in 19th.
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