Chelsea, Arsenal, Manchester City and Liverpool were among the Premier League clubs braced for a busy final 12 hours of the 2017 summer transfer window.
There was a quiet start to Thursday's deadline day as Arsenal's Alexis Sanchez, Chelsea's Diego Costa and Philippe Coutinho of Liverpool all waited to learn if they would be subject of big-money moves before the 2300BST deadline.
Sanchez's future has been in doubt for the best part of a year but losing the Chilean so late in the summer, with little chance of finding a replacement, would sour the mood of Arsenal supporters further.
Particularly damaging would be to sell to a title rival and, while Manchester City is his most likely destination, it is not difficult to imagine Chelsea and Manchester United joining the bidding should Arsenal indicate a willingness to negotiate.
Alex Oxlade-Chamberlain appears likely to make a £40million move from Arsenal to Liverpool, whose resolve to retain Brazil forward Coutinho could be tested by Barcelona.
Costa is in a stand-off with Chelsea and agitating for a return to Atletico Madrid, with a potential deal complicated by the fact the Spanish club are unable to register new players until January.
Swansea striker Fernando Llorente has been linked with a move to Stamford Bridge and a reunion with Antonio Conte, his former boss at Juventus, as Costa's replacement.
But Tottenham are reportedly also eager to secure the services of Llorente.
United, after three wins from three games, appear unlikely to be busy on deadline day, unless an irresistible opportunity arises.
Chelsea, Premier League champions in May, could be the busiest, but Conte insists he will be content even if his thin squad is not augmented.
The likes of Leicester midfielder Danny Drinkwater and injured Everton forward Ross Barkley have also been linked with the Blues.
Drinkwater has handed in a transfer request and Demarai Gray has also asked to be allowed to move on, to Bournemouth, who had a £25million bid rejected on Wednesday.
Riyad Mahrez, a key figure in Leicester's surprise title triumph, has been allowed to leave the Algeria squad and return to Europe to "formalise his transfer to his new club", the Algerian Football Federation announced late on Wednesday.
Mahrez has expressed a desire to leave the King Power Stadium and has been linked with a host of clubs over the summer, with Roma having already had three bids rejected for the 26-year-old, the third for £32million.
The likes of Barcelona, Arsenal, Manchester United and Chelsea are also reported to be interested in Mahrez, who was PFA Player of the Year in 2016.
City's primary focus is likely to be on Sanchez but they are also leading the chase for West Brom centre-back Jonny Evans who, along with Virgil van Dijk, could be at the centre of a late transfer scramble.
Van Dijk's most likely destination is still Liverpool but City, Chelsea and Arsenal have all been credited with an interest in the Southampton defender. Saints are yet to receive a bid for the Dutchman.
Tottenham chairman Daniel Levy has form for leaving deals to the last minute and it would not be a surprise to see the north London club launch a bid for Barkley, who has been on their radar for most of this year. Gray and Liverpool's Divock Origi are potential alternatives.
"Daniel likes to do it on the last day to get the best deal, we just have to wait and see," Spurs striker Harry Kane said.
There is also set to be plenty of activity at clubs lower down the table as a record-breaking transfer window comes to a conclusion.