Manchester City hope to seal a blockbuster move for Enzo Fernandez, while Arsenal have their sights set on Julian Alvarez in the final hours before the transfer window closes.
With Premier League clubs unable to sign players until January once Tuesday's 2200 GMT deadline passes, City, Arsenal and company have one last chance to improve their squads.
Frantic last-minute spending is on the agenda as City try to finally seal a swoop for Chelsea midfielder Fernandez.
Chelsea value Fernandez at around £120 million ($162 million) and City have yet to match that hefty price tag.
A reunion with City's former Chelsea boss Enzo Maresca might suit Fernandez, who had angered the Blues last season by expressing interest in joining Real Madrid.
Maresca is keen to land the Argentine after the recent sale of influential World Cup winner Rodri to Barcelona, as well as the departures of fellow midfielders Bernardo Silva, Nico Gonzalez and Tijjani Reijnders.
Chelsea manager Xabi Alonso has left Fernandez out of his squad for the last two games as speculation swirls over his potential switch to the Etihad Stadium.
City are also expected to announce the signing of Senegal midfielder Iliman Ndiaye from Everton in a deal worth £65 million.
Tottenham had been linked with Ndiaye, but City appear to have won the race for the 26-year-old's signature.
Champions Arsenal can make a major splash if they can land Argentina striker Alvarez.
Alvarez reportedly prefers a move to Barcelona but, while Atletico do not want to sell to their LaLiga rivals, they could be persuaded to do a £128 million deal with Arsenal.
STATEMENT OF INTENT
Alvarez has missed several training sessions and was not part of the Atletico team that beat Sevilla last weekend.
Landing the former City star would be a significant statement of intent from Arsenal, who are looking to win the club's first back-to-back English titles since the 1930s.
Meanwhile, Arsenal striker Ethan Nwaneri is lined up for a season-long loan at Borussia Dortmund.
Liverpool splashed out on France forward Bradley Barcola on Monday, spending £123 million to lure him from Paris Saint-Germain.
But Reds boss Andoni Iraola still wants another winger as the club adjusts to life without Mohamed Salah, who joined Trabzonspor in August after ending his iconic Liverpool career.
Crystal Palace's Ismaila Sarr and Brighton's Yankuba Minteh are on Iraola's wanted list.
If Liverpool sign either of those targets, it could clear the way for Dutch forward Cody Gakpo to leave Anfield amid interest from City and Tottenham.
Harvey Elliott is due to leave Liverpool, with a loan at Valencia lined up for the playmaker after his disappointing stint at Aston Villa last term.
Tottenham are keen to bring in Chelsea winger Mykhailo Mudryk on loan after missing out on Ndiaye.
City winger Jack Grealish is set to rejoin Everton on loan after spending last season with David Moyes's men.
Grealish has fallen out of favour at City over the last two years, but impressed at Everton before suffering a season-ending foot injury in January.
Everton are also on the verge of signing United States forward Folarin Balogun from Monaco in a £40 million deal.
Newcastle striker Nicolas Woltemade is set to join Juventus on loan.