Red Bull's Sergio Perez was fastest in Azerbaijan Grand Prix practice on Friday with his Formula One championship-leading teammate Max Verstappen close behind, while Mercedes failed to make even the top-10.
The Mexican lapped the Baku street circuit with a best time of one minute 42.115 seconds, 0.101 quicker than Verstappen, and looked comfortably ahead.
Mercedes' seven-time world champion Lewis Hamilton, Verstappen's closest rival after five races, was 11th and more than a second off the pace as the once-dominant team struggled again.
His Finnish teammate Valtteri Bottas, the winner last time Azerbaijan hosted a race in 2019, was 16th and more than two seconds slower than Perez. He had been 10th in the first practice. Verstappen had been fastest in the first session with a timing of 1:43.184.
The 23-year-old Dutch driver is four points clear of Hamilton, having seized the lead by winning in Monaco last month while Hamilton finished seventh. Ferrari's Carlos Sainz was third in both sessions.
His teammate Charles Leclerc was second fastest in the first practice and fourth in the afternoon with Ferrari looking the team most likely to be challenging Red Bull for pole position on Saturday.
The "dirty" track proved slippery for drivers, who also had to contend with breezy conditions, as the sport returned to Baku without spectators due to the COVID-19 pandemic.
The weekend has been dominated by a row over "bendy" rear wings, with the governing body FIA keeping a close eye on the situation before introducing new tests at the following French Grand Prix.
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