Sir Lewis Hamilton is facing a crackdown on his wearing of jewellery while driving his Formula 1 car.
The race director for this weekend's Australian Grand Prix, Niels Wittrich, issued a reminder about rules banning body piercing and neck chains that have been in place for years but have not been rigorously enforced.
Seven-time world champion Hamilton, an avid wearer of jewellery outside the cockpit, has been photographed sporting a nose stud while behind the wheel of his Mercedes.
That included at both last year's season-ending Abu Dhabi GP and this year's opener in Bahrain, where it was clearly visible through his open visor.
The Federation Internationale de l'Automobile (FIA) confirmed a nose stud would fall foul of the ban, raising the prospect of Hamilton being forced to remove it.
The rule prohibiting the wearing of jewellery is Article 5 of the third chapter of Appendix L of the governing body's International Sporting Code (ISC).
The full wording of the rule states: "The wearing of jewellery in the form of body piercing or metal neck chains is prohibited during the competition and may therefore be checked before the start."
The FIA first instigated in 2005 what was then described as "an immediate ban on the wearing of jewellery (body piercing and heavy chains) by race and rally competitors", with the rule later adopted into the ISC.
It was brought in to prevent piercings and chains injuring the driver in the event of a collision, and the FIA said it also applied to the wearing of rings and bracelets.
It said there were "lots of instances" of drivers failing to follow the rule and the reminder was not aimed at anyone in particular.
Anyone found to have breached it at the Australian GP would face a fine.
Wittrich is one of two new F1 race directors, in an alternating arrangement with Eduardo Freitas, following the ousting of Michael Masi in the wake of the controversial climax to last season, which saw Hamilton denied a record-breaking eighth world title.
Hamilton is also braced for further misery in Melbourne after his Mercedes team ruled out any major upgrades this weekend.
Hamilton has already been cast 29 points adrift in the championship race after he finished a lowly 10th at the second round in Saudi Arabia a fortnight ago.
Mercedes have dominated the sport since 2014 - carrying Hamilton to six titles and winning an unprecedented eight constructors' championships in succession.
But Hamilton and new British team-mate George Russell have all but written off their aspirations unless Mercedes can radically improve their underperforming car.
Mercedes' season has been derailed by 'porpoising' - the phenomenon seen this year when the car violently bounces on its suspension at high speed.
The problem caught Mercedes completely off guard, and Russell said it is the source of 99 per cent of the team's problems.
It had been suggested that the Silver Arrows would bring a new rear wing and a revised floor to Melbourne for F1's first race Down Under in two years. But it's understood that no big updates are planned for Sunday's race at Albert Park.
