Championship leader Max Verstappen topped both Ferrari drivers to put Red Bull Racing at the head of first practice at the Azerbaijan Grand Prix.

Verstappen’s lap came late in the session, having run the harder compounds early when the street track was at its dirtiest, but his time of 1m43.184s beat Charles Leclerc by just 0.043s.

The Dutchman was comfortably quickest in the first sector but lost time to the Ferrari driver at the second split, which comprises mostly slow-speed corners around the castle section of the track. He lost a little time to his personal best out of the final corner for not having a car to slipstream over the line.

All eyes are on Red Bull Racing this weekend — in particular on its car’s rear wing, which has attracted controversy in recent rounds for appearing to flex beyond what some teams consider the limit of the rules.

Mercedes and other rivals have suggested they could protest the car, but Red Bull has brought an updated design for the unique demands of the Baku circuit that appears slightly less flexible relative to previous versions, which may allay concerns.

Ferrari’s performance also caught the eye, with Leclerc leading teammate Carlos Sainz by around 0.3s. Leclerc set the fastest time of the slow middle sector sufficient to keep him ahead of the field for the balance of the lap. Sergio Perez was fourth in the second RB16 and 0.446s behind his teammate.

Daniel Ricciardo looked strong in fifth for McLaren at 0.548s adrift, though teammate Lando Norris was 0.8s up on the Australian with his fastest lap when he lost control of the car on the apex curb at Turn 16, spinning himself around and rejoining undamaged. He ended the morning eighth.

Finding the limits around this Baku circuit is a perilous business! 😮#AzerbaijanGP 🇦🇿 #F1 pic.twitter.com/HUn2eoKfaD

— Formula 1 (@F1) June 4, 2021

The Briton went off the track again in the final minute when he appeared to become distracted by Valtteri Bottas taking to the run-off at the fast Turn 15, and the two almost came together when the Finn righted his direction.

The dusty and wind-swept circuit caught several more drivers out, and the final 10 minutes of the session saw most of the off-track incidents in the track’s minimal run-off zones.

Nikita Mazepin tapped the wall after spinning backwards at Turn 16, and shortly afterwards teammate Mick Schumacher was reversing his way out of Turn 4. The pair ended the session 20th and 19th respectively.

Pierre Gasly was quick enough for sixth for AlphaTauri after his own off ahead of Lewis Hamilton, whose Mercedes car was most impressive in the power-sensitive first and third sectors despite appearing to run a larger rear wing. Fernando Alonso was ninth for Alpine ahead of Bottas in 10th.

Alfa Romeo teammates Kimi Raikkonen and Antonio Giovinazzi were 11th and 12th after the team scored its first points last weekend in Monaco.

Aston Martin teammates Lance Stroll and Sebastian Vettel were 13th and 15th, the pair split by AlphaTauri’s Yuki Tsunoda in his first visit to Baku. The Japanese rookie spent several minutes stuck in the Turn 4 run-off zone after brushing the outside wall with his left-front tire on entry. He struggled to engage reverse once he’d stopped and then didn’t back up enough when he did find the right gear to make it back onto the track, causing a lengthy yellow flag.

Esteban Ocon was 16th for Alpine ahead of Williams teammates George Russell and Nicholas Latifi and the Haas teammates.