The Pacific Consortium -- consisting off Kohlberg Kravis Roberts, Macquarie Group, First State Superannuation Scheme and North Haven Infrastructure Partners -- made an all-cash bid of Aus$7.2 billion, a sweetened offer from last year's cash and scrip offer.
An all-cash bid does not require regulatory approvals.
Tatts had rejected the consortium's first proposal in December and said it was not superior to a tie-up with Tabcorp, which the firms have pursued for years in a bid to cut costs and chase opportunities globally.
But today Tatts said in a statement it "is undertaking a full analysis of its key terms, underlying financial assumptions and conditions". The fresh Pacific Consortium bid values each Tatts share at Aus$4.21.
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"Once this review is complete, an update will be provided to the market."
Under the previous proposal, Tatts was valued at between Aus$4.40-$5.00 per share. The Tabcorp merger valued Tatts at Aus$4.34 per share.
Tatts' stock prices jumped 1.61 percent to Aus$4.42 today, while Tabcorp fell 0.63 per cent to Aus$4.70.
Tabcorp has also lodged an application with the Australian Competition Tribunal, which hears applications for review of ACCC decisions, for merger approval.
Tatts Group has a betting shop network in the states of Queensland, South Australia and Tasmania and also operates a lotteries business.
Tabcorp Holdings runs similar operations in Victoria and New South Wales, with a broadcasting and media arm built around Sky Racing.