Private equity group Terra Firma and medical charity the Wellcome Trust have confirmed they are considering a rival takeover bid for Alliance Boots.
The battle for Boots appears to be hotting up
The pair are "in the early stage of assessing" the pharmacy group, but stressed it may not lead to a bid.
Any offer from the consortium would need to trump a £10bn, 1,040p-a-share bid tabled by Kohlberg Kravis Roberts (KKR) and Italian Stefano Pessina.
If KKR is successful it plans to take the Alliance Boots private.
Mr Pessina, who already owns a 15% stake in the health and beauty group, is said to want to take Boots private to enable it to grow away from the public spotlight.
The Wellcome Trust and financier Guy Hands' Terra Firma - which owns Odeon and UCI cinemas as well as waste management firms - confirmed they were considering a possible bid for Boots following widespread speculation over the weekend.
The consortium is believed to have asked Boots for access to its books on the same basis as KKR.
According to reports, the Boots board is considering the demand and will allow Terra Firma access to the books if it is convinced the consortium has or can get sufficient financial backing to mount a credible bid.
A decision on whether Wellcome and Terra Firma will be allowed to see the books is expected by Friday.
However, reports suggest German drugs company Celesio, which owns the UK's Lloyds pharmacy group, may also come forward with a possible approach.
Alliance Boots is best known in the UK for its 2,600 Boots the Chemist shops on the High Street, but it also has 400 overseas outlets in countries including Thailand and Italy.
The group, which was created in a £7bn tie-up with chemist chain Alliance Unichem last year, supplies more than 125,000 pharmacies, health centres and hospitals.