BBC Wales Sport has reported that the national stadium in Wales is a strong favourite to host European club football's flagship match.
Uefa, European football's governing body, will make an official announcement on Monday, 29 June in Prague, Czech Republic.
The Football Association of Wales has been leading the bid to host one of Uefa's major finals - the Champions League or Europa League.
The Welsh Rugby Union - as owner of the Millennium Stadium - has offered its support, with chief executive Roger Lewis telling the BBC in May that "the noises we are getting at the moment are hugely encouraging".
"I'm feeling very good about bringing quality European football to the Millennium Stadium," he added.
The 74,500-capacity Millennium Stadium missed out on hosting matches for the 2020 European Championship.
But the venue has hosted a wide range of events including the FA Cup final, League Cup final, Community Shield and
Football League play-offs from 2001 to 2006, while Wembley was being redeveloped. Olympic football matches were played there in 2012.
Cardiff City Stadium played host to the 2014 Super Cup, in which Real Madrid - the club of Wales star Gareth Bale - beat Sevilla.