Red Bull's Formula 1 driver pairing of Max Verstappen and Sergio Perez have not appeared best pleased at the reigning constructors' champions so far this weekend in Mexico City.
The pair endured tricky practice sessions across Friday and Saturday's proceedings, the RB20 frequently prompting severe complaints from the stars over team radio.
As the pair took to the track on Friday for the first practice session of the Mexican GP weekend, Christian Horner would no doubt have expected show-stopping performances from both drivers, most notably Perez, always eager to impress in front of his home crowd.
This year especially, the Mexican star will be hoping to put to bed the persistent rumours that multiple drivers on the grid, from in and outside of Red Bull's talent pool, are competing to replace him as Verstappen's team-mate.
By close of the session however, Red Bull had been left rather humiliated, the Dutchman only managing to set the fourth fastest time after he was forced to return to the garage when his Red Bull experienced major power issues.
Hoping to start Saturday's runs with a clean slate, the pair headed into FP3with high hopes, particularly three-time champion Verstappen, after the team changed the power unit on his machinery ahead of the final practice session and qualifying for Sunday's race.
The change is yet to prove fruitful however, with Verstappen still reporting complaints over team radio.
"Ah this doesn’t **** work, there’s no grip [in the tyres] front or rear" the champion declared.
Affairs out on track didn't seem much better for his team-mate either, with home favourite Perez stating: "Yep there’s no potential on the front to attack the braking."
Verstappen finished the final practice session almost half a second behind Lando Norris, with Perez over a second adrift of the McLaren.