Reports in Colombia have claimed that City Football Group could be considering a bid of around €90 million (£78.5m) for the Bogotá club. El Futbolero reported that CFG, which owns Manchester City and several other clubs around the world, had entered the picture as Millonarios' ownership situation developed.
The reported figure has subsequently generated wider discussion about what Millonarios could look like as part of the City Football Group network, particularly in relation to the club's academy and sporting structure.
However, there is currently no independent confirmation of the reported €90m offer or of how advanced any discussions with CFG may be.
There is considerably more evidence of activity involving Kapital Football Group, an investment vehicle connected to US group DaGrosa Capital Partners.
Kapital executive Hugo Varela was pictured at Millonarios' El Campín stadium last weekend alongside figures from the Colombian club, while reports have described negotiations between the two parties as advanced.
Millonarios' majority shareholder is Amber Capital, which controls 86.1 per cent of the club, and the possible sale has been the subject of increasing speculation in recent weeks.
Millonarios director Gustavo Serpa has acknowledged that an offer exists and described it as "interesting", although the process remains subject to further checks and negotiations.
Reports have placed different valuations on the Colombian club, with figures ranging from roughly €55m to €68m in recent coverage. A separate report suggested Amber Capital was working around a valuation of US$65m to US$80m.
The distinction is important because Kapital currently appears to have a more developed position in the process than CFG.
If the reports of City Football Group's interest are eventually confirmed, however, the proposed takeover would add another South American club to CFG's expanding global network.
It would also create an unusual dynamic, with Kapital's own multi-club ambitions reportedly drawing inspiration from the City Football Group model.
For now, Millonarios' ownership remains unresolved, with the Colombian club still going through the due-diligence process connected to the proposed sale.