NBC and Universal Pictures owner Comcast has made a £22.1 billion takeover approach for Sky in an attempt to trump 21st Century Fox's efforts to seize full control of the UK broadcaster.
The US media giant behind cable channels MSNBC and CNBC is eyeing a possible cash offer of £12.50 per share, a 16% hike on Fox's bid of £10.75 a share.
The group wants to snap up a majority stake in the Game Of Thrones broadcaster - more than 50% - and was confident a deal would be given the green light by regulators.
Such a move would place Sky at the centre of a full-blown takeover tussle, with Rupert Murdoch's Fox struggling to buy the 61% of the broadcaster it does not already own due to mounting regulatory hurdles.
Comcast said its offer would be a 13% premium of Sky's closing share price of £11.05 on Monday.
Comcast chairman and chief executive Brian Roberts said Sky is "an outstanding company".
He said: "We think that Sky would be very valuable to us as we look to expand our presence internationally.
"The superior cash proposal values each Sky share at £12.50 in cash - a significant premium to the 21CF price currently recommended.
"We would like to own the whole of Sky and we will be looking to acquire over 50% of the Sky shares. We are confident that we will be able to receive the necessary regulatory approvals. If successful, the acquisition will enhance our free cashflow per share in the first year.
"The UK is and will remain a great place to do business. We already have a strong presence in London and Comcast intends to use Sky as a platform for our growth in Europe.
"We intend to maintain and enhance Sky's business."