For so long we have been used to seeing Mercedes cars at the top of the timesheets in the hybrid era, but its dramatic struggles during Friday practice left a real sense of confusion throughout the Baku paddock. 

Following its lacklustre performance at Monaco last time out, Mercedes had hoped to bounce back strongly around the streets of Baku, a venue where it has claimed four out of five victories since Azerbaijan joined the F1 calendar in 2016. 

Despite struggling for competitiveness in Monte Carlo, Baku’s street circuit provides a vastly different challenge through its combination of slow-speed sections mixed with long straights. 

But on Friday at least, Mercedes was absolutely nowhere. Overall, it was the seventh-fastest team on the softs as it failed to unleash any single-lap pace.

World champion Lewis Hamilton was a second off the pace-setting time of Red Bull’s Sergio Perez and only 11th fastest. 

And things were even worse for teammate Valtteri Bottas, who was a further second away as he found himself in unfamiliar territory down in 16th. 

Both Hamilton and Bottas were left baffled as to why they were unable to extract any sort of competitive lap time on the soft tyre, having also struggled in FP1, finishing seventh and 10th respectively. 

"Today was our worst Friday by some margin,” admitted Mercedes trackside engineering director Andrew Shovlin.

“Our biggest issue seemed to be the single lap; we're a long way from our normal positions so clearly we need to find something very significant there. The long run picture was not as bad - a fair bit behind Red Bull but still in the mix. 

"So, lots to work on overnight; we're planning a comprehensive programme of analysis and simulator work to try and understand some of these issues but we clearly have an awful lot to find.”

Indeed, the analysis started immediately after the chequered flag fell in FP2, with team boss Toto Wolff initially refusing to speak to the media as he rushed to the debrief to try and establish what exactly had gone wrong. 

Aside from lacking outright pace, seven-time world champion Hamilton said it had otherwise felt like a “really good day” as he ended up 0.9s behind main title rival Max Verstappen

“In this one [FP2] there was just no more time in it.

“We’re definitely quite a chunk down and I think everyone will be scratching their heads and looking into the data trying to figure out how we can improve.” 

Bottas added: “It was very, very tricky for us today and clearly we were lacking pace. It feels like it's just overall grip, you know.

“The balance is not that far off. Okay, the car is maybe a bit unpredictable, but it just feels like lacking grip and sliding around. So I think it's gonna be a long night tonight.”

Asked if things were any better on the long runs, the Finn said: “Slightly better maybe on the long run, but still, we're lacking pace. That's for sure. 

"So I think there's something fundamentally wrong and we need to figure out what.”

Wolff acknowledged that Mercedes is likely to face its “most difficult” qualifying session since the 2015 Singapore Grand Prix in Azerbaijan. 

“We knew that Monaco and Baku were not tracks that suit us,” he said. "They [Red Bull] were very good in those twisty parts of Monaco, so they are very good here too, Ferrari also. 

“And then on the straights, if you have a wing that gives you this additional speed, you have the perfect combination against us. 

“So you just have to take it on the chin and try to give it the best performance and collect the most points.”

It will be a very long night for Mercedes, who will have to pull off a gargantuan turnaround if it is to find itself fighting for pole come qualifying.

What else did we learn on Friday in Baku?

While Mercedes struggled, the opposite was true for Red Bull, who cemented itself as the team to beat in Baku. 

Perez said he enjoyed his “best Friday of the season” after topping the timesheets in FP2, adding he now finally feels at one with his RB16B car. 

The Mexican ended up a tenth clear of teammate Max Verstappen, while Ferrari had a promising day as it appeared to carry over its strong Monaco form into the Azerbaijan Grand Prix. 

Carlos Sainz finished third in both FP1 and FP2, with teammate Charles Leclerc taking fourth in the afternoon despite crashing into the Turn 15 barriers on what would have been his fastest lap. 

Ferrari could end up being the second-best team should Mercedes’ woes continue on Saturday, though both Sainz and Leclerc are remaining cautious about their chances. 

Despite many tipping McLaren to be serious challengers at the front of the field in Azerbaijan, Lando Norris thinks the Woking squad is “too far away to do anything special” after ending the day eighth. 

There was little separating AlphaTauri’s Pierre Gasly, Alpine’s Fernando Alonso and Norris in FP2, while Antonio Giovinazzi also put his Alfa Romeo in the mix during a tight session. 

Once again, the battle to land a Q3 spot looks set to be a closely-contested affair in qualifying.