Private equity group Terra Firma and medical charity the Wellcome Trust have announced they may attempt a takeover bid for Alliance Boots.
According to reports the pharmacy group is now considering whether to open its books to the two potential bidders.
The company previously agreed to do so last month following a second takeover offer made by Kohlberg Kravis Roberts (KKR) and Italian billionaire Stephano Pessina, who already owns substantial shares in Alliance Boots - the result of a previous merger between his wholesale company Alliance UniChem and pharmacy chain Boots.
Any offer made by the Wellcome Trust and Terra Firma, whose portfolio includes the Odeon and UCI cinemas, would need to top the latest 1.040p a share bid made by KKR and Mr Pessina, which values Alliance Boots at £10 billion.
But in a statement the two groups stressed that they were in the "early stages" of assessing Alliance Boots and warned that a bid might not be made for the company, which owns the Boots the Chemist chain and also supplies pharmacies, health centres and hospitals.
"No decision has been made regarding the merits of making an offer for Alliance Boots and as a consequence there can be no certainty that an offer will be forthcoming," Terra Firma and the Wellcome Trust said in a statement.
Meanwhile, amid further signals that Alliance Boots could become the focus of a bidding war, reports suggest that German drugs company Celesio, owner of the Lloyds pharmacy group, may yet make its own takeover offer.