The club most likely to be unaffected by the credit crunch is Manchester City, who may still be serious under-achievers at the wrong end of the Premier League, but became the world's richest club when they were bought by Sheikh Mansour bin Zayed al Nahyan of Abu Dhabi last year.
They have been linked with more than 50 players in the build-up to the January transfer window including Thierry Henry and Lionel Messi of Barcelona, Kolo Toure of Arsenal and Roque Santa Cruz of Blackburn Rovers.
European champions Manchester United, meanwhile, are unlikely to spend much this month with manager Alex Ferguson saying this week he was happy with his squad. Ferguson spent nothing last January and so far has indicated that only teenage Serbian winger Zoran Tosic is moving to Old Trafford.
Liverpool, the English league leaders, have been linked with a number of players including a return to Anfield for Wigan striker Emile Heskey but Arsenal manager Arsene Wenger could be the busiest among England's Big Four.
With Theo Walcott, Tomas Rosicky and Cesc Fabregas all out through long-term injuries, Wenger could move for Zenit St Petersburg's Andrei Arshavin, while David Villa of Valencia and Daniele De Rossi of Roma have also been mentioned as targets.
Italian plans
The transfer window looks set for a slow start in Italy however, where Milan are the only leading Serie A side to have said that they want to do business in January.
Chief executive Adriano Galliani said on Monday that the seven-times European champions are looking for a left-back but the Italian media has suggested that Liverpool centre-back Daniel Agger is their top target amid uncertainty about Alessandro Nesta's return from a stubborn back problem.
With Gennaro Gattuso out for six months after knee surgery, an extra midfielder could be useful too. Coach Carlo Ancelotti has said David Beckham can provide cover, but the Englishman is only staying for a few months on loan from LA Galaxy and doubts remain about whether a winger can fill Gattuso's central role.
Juventus are thought to be looking for a defender too with Dario Knezevic and Jonathan Zebina expected to remain unavailable with injuries until March.
The Turin club have their sights set on Portuguese centre-back Manuel da Costa, who is struggling for a place at Fiorentina, while Juve are also hoping to take advantage of Valencia's financial problems to land midfielder David Silva.
Inter's dealings will depend on whether Adriano moves on after irritating coach Jose Mourinho with repeated indiscipline.
The leaders are being linked with Genoa's Diego Milito, although club president Enrico Preziosi said he would not sell the Argentine forward for €30 million ($42.55 million).
Real Madrid have dominated the transfer news in Spain as the injury-hit Primera Liga champions seek to boost their chances of closing the 12-point gap to leaders Barcelona.
The club is locked in a dispute with UEFA over whether the two signings already agreed - striker Klaas Jan Huntelaar from Ajax and midfielder Lassana Diarra from Portsmouth - can both play in the Champions League. New Real coach Juande Ramos has said he is also interested in signing a winger and players named in the Spanish media as possible targets include Aston Villa's Ashley Young, Liverpool's Jermaine Pennant, Aaron Lennon from Ramos's previous club Tottenham Hotspur and Wigan's Antonio Valencia.
German champions Bayern Munich have warned their fans not to expect too many signings but they have targeted SV Hamburg striker Ivica Olic, who has had an outstanding season so far, to partner Luca Toni and Miroslav Klose up front.
"We have said we are interested (in Olic). Now we have to wait and see how things unfold," Bayern chairman Karl-Heinz Rummenigge said recently.
German media have also reported an interest by Bayern in Chelsea's Florent Malouda.
Bayern striker Lukas Podolski could move from Munich back to Cologne, his former club, if the price is right, especially since the arrival of another striker, Landon Donovan, who recently joined the champions on loan from LA Galaxy.
Surprise league leaders Hoffenheim, who signed former Germany keeper Timo Hildebrand in December, want to strengthen their squad with a central defender and a left-back ahead of what could be their first Champions League experience next year.
In France, seven-times champions Olympique Lyon are ready to spend to make their mark on the European stage at last and will not be put off by the financial climate, chairman Jean-Michel Aulas told daily L'Equipe last week.
Aulas hinted Lyon would first try to sign defenders and would not let last season's top scorer Karim Benzema go.
Fernando Cavenaghi's agent told France Football magazine the Argentine striker would be keen to leave Bordeaux for Tottenham if the Premier League club confirm their interest in the player, who has also been linked with a move to Liverpool.