Mercedes have been lacking pace all season but appear to finally be in contention following make-or-break upgrades in America, where a genuine three-team battle could headline a much-anticipated street race.

Russell led Mercedes' charge on Friday and, after placing second in the opening session, was fastest overall in the cooler P2, beating Charles Leclerc by a tenth of a second with his 1:29.938.

Sergio Perez was third for Red Bull, with Lewis Hamilton fourth and two-tenths off his young Mercedes team-mate Russell, who he also trails in the championship.

But in truth, Mercedes could not have asked for a better start to the weekend - particularly as F1 2022's fastest teams Ferrari and Red Bull both suffered in second practice.

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Carlos Sainz, after back-to-back shunts in Australia and Imola, crashed his Ferrari to bring out a red flag, while Max Verstappen completed only one disrupted lap in the session with reliability issues.

In Sainz (11th) and Verstappen's (19th) absence from the front, Fernando Alonso and Lando Norris ensured Alpine and McLaren go into the weekend with high hopes after placing fifth and sixth, while Pierre Gasly wasn't far behind in a competitive AlphaTauri.

Valtteri Bottas, like Verstappen, didn't get a time on the board at all, failing to even make it out of the garage after his P1 garage.

The return of Mercedes: Fast Miami start as Ferrari and Red Bull suffer

While they have two podiums this year, Miami marks the first time Mercedes go into a weekend as genuine challengers for Ferrari and Red Bull - and given their form on Friday they could even be favourites.

How, then, have Mercedes gone from their myriad of problems to frontrunners?

The answer is likely two-fold. Mercedes have various upgrades for Miami's F1 debut - including a substantially-different new front wing - which appear to have done their job in improving the 'porpoising', Silver Arrows' biggest issue.

The track may also be a factor, with a low-downforce setup - despite the higher top speed - seemingly also relieving the violent bouncing.

Either way, Mercedes are now very much a factor for their rivals, particularly given their stop-start Fridays.

Ferrari will be satisfied but not pleased with their pace while their weekend was made harder by another error by the under-pressure Sainz, who took way too much speed into Turns 12 and 13 and ended in the barriers.

"I don't know what happened there," said the Spaniard.

Red Bull, meanwhile, have more reliability concerns on their hands as Verstappen didn't manage to turn a wheel in anger in P2.

In a bizarre sequence of events, Red Bull kept Verstappen in the garage at the start of the hour-long session for a precautionary gearbox change before releasing him, but Verstappen soon reported that he couldn't steer his car.

Following a very slow lap where he almost had an incident with Lance Stroll and saw his brakes catch fire, Verstappen returned to the pits and wouldn't be seen on track again.

Christian Horner told Sky Sports F1 that it was a hydraulics issue, which also caused damage to the brakes.

For the first time this year, Mercedes are the team to beat heading into a weekend. Watch all the Saturday action live on Sky Sports F1, with final practice at 6pm before qualifying at 9pm.