BBC Sport football news reporter
The Premier League have written to Chelsea to seek clarification over the club's position with ticket re-sellers - amid controversy over Todd Boehly's involvement in Vivid Seats.
Boehly is both a director and investor in Vivid, described as an "unauthorised ticket seller" by the league, and also owns a 13% stake in Chelsea.
The website lists Chelsea matches on its platform, with some tickets last season at Stamford Bridge going for as much as £20,000. It is not allowed to operate in the United Kingdom, although is permissible overseas.