The Reuben brothers are leading the chase for Scottish & Newcastle, the £2.3bn managed house business currently up for sale.
According to The Sunday Times newspaper, the secretive billionaires threw their hats into the ring in the late stages of first round bidding.
The brothers are said to have made the highest bid so far for the 1,500 pubs.
The mantle was previously held by Pubmaster, which had indicated it would be willing to pay between £2.3bn and £2.5bn.
The other main rival to the Reuben brothers is PAI, the French private equity firm.
Laurel Pub Company is understood to be working with Japanese bank Nomura, and Mitchells & Butlers is also believed to be a strong contender.
The prize is widely acknowledged as the best managed house business in the UK, and includes brands such as Chef & Brewer and the Premier Lodge chain.