The January transfer window in Europe opened on Friday, with the bulk of the spending set to be done by clubs in the English Premier League.
Among the continent's leading nations, clubs in Spain will be the first ones to be able to sign reinforcements, with the window there opening on Friday and shutting on January 30.
In England, Germany and France, the window opens on Saturday, January 3 and will not shut until Monday, February 2, while a shorter window in Italy opens from January 5.Premier League teams splurged a record 835 million pounds ($1.3 billion, 1.075 billion euros) in the summer and they should again be the busiest in this shorter window.
Most of the movement is unlikely to come before the final, crazy days of the window, but in the meantime much of the talk will surround Manchester United, who are said to have no upper limit on the amounts they can spend.
The Old Trafford club spent a net sum of 122 million pounds in the summer, but manager Louis van Gaal still needs to strengthen at the back in particular.
He has been linked with moves for fellow Dutchman Ron Vlaar, of Aston Villa, and Borussia Dortmund's Mats Hummels, while Dutch midfielder Kevin Strootman of Roma is another target.
Elsewhere, Manchester City's spending potential is limited because of Financial Fair Play, but Chelsea are set to sign Croatian striker Andrej Kramaric from Rijeka for 7 million pounds and loan him to Dutch side Vitesse Arnhem.
Southampton have agreed a deal to bring in Dutch winger Eljero Elia on loan from Werder Bremen and new managers - Tony Pulis at West Bromwich Albion and Alan Pardew at Crystal Palace - will be given funds.
In contrast, Liverpool manager Brendan Rodgers has said he will be quiet this month.
"There won't be a lot of activity, if any, in January," he said. "I don't think it is a good time to spend. Last year we never brought anyone in.
"We brought in a lot of players (in the summer) who we felt could develop and they are starting to adapt. My job is to coach and manage the players here and maximise that talent."
Khedira, Alves on the move?
In Spain, Real Madrid are seemingly focusing their energy on the pursuit of Borussia Dortmund and Germany star Marco Reus while dismissing suggestions they will allow Gareth Bale to depart.
"We would never listen to any offer for Bale regardless of the amount," said Madrid president Florentino Perez.
Nevertheless, midfielder Sami Khedira is out of contract in the summer so can now negotiate his next move, and the reigning European champions could replace him with Brazilian prospect Lucas Silva, of Cruzeiro.
Meanwhile, Barcelona cannot sign any new players until 2016 after the Court of Arbitration for Sport upheld a one-year transfer ban imposed by Fifa for breaching rules on signing youth players.
Instead they must focus their energy on offering new terms to right-back Daniel Alves, who is out of contract in the summer.
Atletico Madrid have already moved to bring back former idol Fernando Torres, who arrives after a disappointing six months in Italy with AC Milan.
Moving in the other direction is former Torino man Alessio Cerci, who only departed Serie A in the summer.
Much of the transfer speculation in Italy surrounds champions Juventus, who appear unlikely to get Bayern Munich's Xherdan Shaqiri but have been linked with a move for Galatasaray's Wesley Sneijder, and Inter, who recently brought back Roberto Mancini as coach.
January is not usually a busy time in Germany, where Bayern are likely to be busiest trying to offload Shaqiri, while Wolfsburg have signed China midfielder Zhang Xizhe and struggling Dortmund have captured Slovenia midfielder Kevin Kampl from Salzburg.
In France, Paris Saint-Germain - hampered by Financial Fair Play restrictions - need to sell before they can buy, while Lyon president Jean-Michel Aulas has dismissed claims that he will listen to offers for leading scorer Alexandre Lacazette.
However, Andre-Pierre Gignac and Andre Ayew will be out of contract at Ligue 1 leaders Marseille in the summer so can negotiate moves elsewhere.