Nike told their players to bring the dresses to their rented house close to the All England Club for alterations.
An email from its sports marketing team sent to players and their representatives, seen by the Daily Mail, says: 'We need to make a small change to your dresses per Wimbledon rules. Could you please bring them by the Nike Wimbledon House.'
In thick, underlined type there then follows the message 'this is VERY important'.
Eugenie Bouchard and Laura Robson are among the stars expected to have their dresses lengthened by the sportswear firm.
Wimbledon has a famously strict all-white dress code which states that 'common standards of decency are required at all times'.
Serena Williams, the company's highest profile endorsee in the event, will wear a slightly adapted version of the outfit, the 'Nike Women's Premier Wimbledon Serena SW19 Dress'.
The £100 dress is more structured and features a nipped in waist and a higher neckline.
An All England Club spokesman described it as a matter for Nike.
'We approved it because it fully complies with our colour regulations,' he said.
Nike declined to comment when approached on Wednesday.