Nico Rosberg and Lewis Hamilton put on an ominous show of force for Mercedes on Friday as Australian Grand Prix free practice was overshadowed by a legal row engulfing Sauber.
The Silver Arrows picked up where they left off last season, knocking Sebastien Vettel and Kimi Raikkonen's Ferraris off the top in the second session as they led both practices.
But events off the track dominated as the extraordinary dispute over Sauber's driver line-up headed into a sixth day with threats of fines, jail and seizures of assets.
Giedo van der Garde's lawyers argued Sauber was in contempt of court by not complying with an order to honour a contract with the Dutchman and let him drive in the season-opener.
As the case unfolded, Van der Garde walked the paddock in Sauber overalls and drivers Felipe Nasr and Marcus Ericsson sat garaged in stationary cars during opening practice.
But Nasr and Ericsson both drove in the second session, as the contempt hearing was adjourned until Saturday and the judge urged the two sides to pursue "sensible" discussions.
Sauber team principal Monisha Kaltenborn was forced to defend her position with the Swiss outfit in disarray, after apparently signing up three drivers for their two cars.
Kaltenborn, who should be fined or jailed according to Van der Garde's lawyers, insisted she had not considered resigning. But she admitted the row had affected the team.
"It's definitely a very negative impact on the team," she said, as she fended off a barrage of questions at a press conference.
'Ants in pants'
On the track, it was business as usual for Mercedes as Rosberg, last year's race-winner, led Hamilton in the first two practice sessions of the new season.
Rosberg hailed a "great start for the team" and said it was again be a close-run thing with Hamilton, who sealed last year's title in the final race.
"It seems again that it's very close between Lewis and me and he is a great driver, so I need to nail the set-up every time to come out on top," Rosberg said.
Hamilton said he was still working on set-up issues and warned that Mercedes would not be the only fast cars in qualifying on Saturday.
"Today (Friday) seemed to confirm that we have pretty good pace. But there are still other quick cars out there and we can't go into tomorrow's (Saturday's) sessions not thinking that they will be close," Hamilton said.
Rosberg clocked 1 min 27.697sec in the second session, one-tenth faster than Hamilton, after shading his team-mate and fierce rival by three-hundredths in the first run-out.
Four-time world champion Vettel had an encouraging start with Ferrari when he finished six-hundredths off the two Mercedes in the second run, closely followed by Raikkonen.
"I can't think of such a trouble-free Friday session in a long time," said Vettel, who shifted from Red Bull in the close season.
And Vettel's former team-mate Daniel Ricciardo had a frustrating day when he missed the second practice session after his Red Bull needed a change of Renault engine.
"I've got to get these ants out of my pants now - I'm hanging out to drive!" said the Australian.
The second session was stopped when McLaren's Kevin Magnussen, deputising for Fernando Alonso after his crash in testing, came off into the gravel at Turn 6.
Three-time race winner Jenson Button reported understeer problems with the other McLaren and Felipe Massa missed the second session due to a water leak in his Williams.
Day one of the 2015 season was not good for Manor, formed from the ashes of bankrupt Marussia, when they missed both sessions because of severe software problems.
Toro Rosso's Max Verstappen, set to become the youngest ever Formula One driver at 17 years and 166 days on Sunday, was sixth fastest in the first session but 14th in the second.
Sauber was earlier forced to hand over a list of assets to ensure it complies with this week's Australian court order, raising the threat of seizures.
But the two sides were reportedly engaging in constructive dialogue as hope rose for an amicable outcome.