UK payments processor Worldpay has been granted the second extension for its merger talks with US suitor Vantiv as the firms haggle over terms of the £9 billion deal.
The last-minute extension sees Vantiv given until 5pm on August 11 to make a firm offer or walk away under City takeover rules.
Worldpay said "positive discussions" are continuing between the two companies as they thrash out the final details.
The deadline change means that earnings for both Worldpay and Vantiv will now be pushed back to Wednesday.
Cincinatti-based Vantiv reached a preliminary agreement last month on the tie-up, which would see it pay 385p a share for Worldpay, or £7.7 billion, plus £1.4 billion to cover debts, valuing the British group at £9.1 billion.
But the pair are reportedly still working on terms, including the protection of British jobs and employees.
The merger would create a trans-Atlantic payments processing giant with a combined market value of more than 20 billion US dollars (£15.5 billion).
Under terms of the proposed deal, FTSE 100 firm Worldpay will delist from the London stock market, but will be run by two chief executives and co-headquartered between London and Vantiv's base in Cincinatti.
Worldpay shareholders would own around 41% of the combined group under the deal with Vantiv.
The firms said last month the proposed deal "creates a scale world-class payments group in a dynamic market".
Worldpay processes millions of payments a day in stores, online and on mobile phones.
It was owned by Royal Bank of Scotland until the state-backed lender sold off its remaining stake to private equity firms Advent International and Bain Capital in 2013.
The company later sealed the biggest flotation of 2015 when it listed on the London Stock Exchange with a valuation of £4.8 billion.
Vantiv is based in Ohio and handled 25 billion transactions worth 920 billion US dollars (£711 billion) last year.
It is largely focused on the US, helping merchants, banks and credit unions accept card payments, as well as gift cards and online payments.
After its potential merger with Vantiv, the enlarged group would be led Worldpay's current boss Philip Jansen as co-chief executive and Vantiv's Charles Drucker as executive chairman and co-chief executive.
Worldpay chairman Sir Michael Rake and his counterpart at Vantiv, Jeffrey Stiefler, will remain on the board as non-executive directors.
But Worldpay announced on Monday that the head of its UK division, Peter Jackson, is leaving to become chief executive of gambling giant Paddy Power Betfair, replacing outgoing boss Breon Corcoran.