Roger Federer received orders from Wimbledon organisers on Wednesday to change his orange-soled shoes that breach an all-white rule although women players like Maria Sharapova will not be pulled up for wearing coloured underwear.
Wimbledon, the world's oldest tennis tournament, has the strictest dress code in tennis, stating for the past 40 years that players must wear "predominantly" white.
The rules stipulate no solid mass of colour, no fluorescent colours, little or no dark and bold colours, and preferably all white shirts, shorts and skirts.
The tournament's clothing police allow no exceptions, even for top players like Federer, the seven-times champion ranked the world's eighth most powerful celebrity by Forbes magazine this week.
"He has been asked to change his shoes," said a Wimbledon spokesman ahead of the Swiss player's match on Wednesday against Ukrainian Sergiy Stakhovsky on Centre Court.
He said several other players had also been asked to change their shoes to abide by the rules but no other warnings had been issued for other violations of the dress code.
The sight of coloured knickers emerging as women rivals Maria Sharapova from Russia and American Serena Williams serve failed to make organisers see red and the coloured nails sported by a list of women players on court have not been ruled out.
Knickers have caused a stir at Wimbledon in the past, dating back to 1949 when American Gussie Moran was accused of "putting sin and vulgarity into tennis" by wearing lace-trimmed knickers at the All England Club in south London.
KNICKERS, LOGOS AND STYLE
Six years ago Frenchwoman Tatiana Golovin shocked organisers by wearing a pair of crimson underpants beneath her white outfit which had officials reaching for the rule book but to no avail.
"The rules state that players can wear any colour underwear they like provided it is no longer than their shorts or skirt. Anything else must be white," said a Wimbledon spokesman.
The all-white dress code is one of the traditions at Wimbledon, which dates back to 1877 when women wore ground-length dresses on the court, and officials are keen to uphold standards.
In 1985 the U.S. player Anne White was called to one