The transfer window in England opened on June 14 and for the major leagues in Europe it will open on July 1.
Lionel Messi and Karim Benzema have already kicked off the window in spectacular fashion, and more of football's biggest stars could also be on the move this off-season.
Kylian Mbappe has told Paris Saint-Germain he will not sign a 12-month extension on his current contract, which is expected to spark an auction for the France striker, with Real Madrid likely to be at the head of the queue.
The Spanish club is in need of a center forward following Benzema's move to Saudi Arabian champion Al-Ittihad.
Madrid, along with Manchester United, has also been linked with Harry Kane, who has a year to run on his deal at Tottenham.
United is also trying to sign Chelsea midfielder Mason Mount.
Manchester City needs to add to its midfield, with Ilkay Gundogan leaving for Barcelona.
City is among a host of teams linked with West Ham midfielder Declan Rice, along with Arsenal, United and Bayern Munich.
Here are some of the biggest potential transfers to watch out for:
Kylian Mbappe (Paris Saint-Germain)
Mbappe is widely expected to take over from Messi and Cristiano Ronaldo as football's biggest superstar and has put Europe's biggest teams on alert after announcing he will not sign a new deal with PSG.
Out of contract next year, he will be a free agent. PSG does not want to risk losing him for nothing, which could see him put up for sale soon if a new deal cannot be agreed.
Madrid had a bid of $190 million rejected in 2021 and the timing would appear to be perfect to launch a fresh move after Benzema's exit.
Mbappe, however, says he will see out the final year of his deal.
Harry Kane (Tottenham Hotspur)
After years of speculation about his future, Kane could finally leave Tottenham. With a year on his contract, the pressure is on Spurs chairman Daniel Levy to either sign him to a new deal or cash in.
Madrid and United continue to be linked with him, with Tottenham reportedly valuing its all-time leading scorer at about $127 million.
Both of those clubs are in the market for a new striker. Madrid needs to replace Benzema, while United still hasn't filled the void left by Cristiano Ronaldo's departure last year.
Perhaps PSG could be added to the list of potential suitors if Mbappe does leave this year.
Kane has never won a major trophy and turns 30 before the start of next season, which is another reason why the time might be right to make the move.
Declan Rice (West Ham)
Jude Bellingham’s move to Real Madrid has left Rice as probably the most wanted midfielder in Europe.
Arsenal and City are reportedly leading the race for the England international, who has also been linked with United and Bayern Munich.
He led West Ham to triumph in the Europa Conference League, which was widely considered to be his final act for the London club.
City is in the market for a top midfielder following the departure of Gundogan to Barcelona, while Arsenal has also made that area a priority after finishing runner-up in the Premier League last season.
Neymar (Paris Saint-Germain)
Messi and Mbappe have dominated the headlines as far as PSG is concerned ahead of the transfer window, but Neymar's future also remains uncertain.
The French champions are planning a change of strategy, which focuses on young and home-grown talent. Neymar would not appear to fit that shift in direction, so could potentially follow Messi by becoming the next star name to depart.
Much could depend on who wants the Brazilian, with Saudi Arabia already linked with a move for him as part of the country's ambitious recruitment drive.
Josko Gvardiol (RB Leipzig)
Having won a treble of trophies last season, it is hard to know how Pep Guardiola can improve his all-conquering Manchester City team.
Gvardiol, who was one of the stars of last year's World Cup, could be one way.
The Croatia defender has continually been linked with a move to City in what could be a world record fee for a defender, with Leipzig reportedly wanting more than the 80 million pounds (then $97 million) United paid for Harry Maguire in 2019.
Romelu Lukaku (Chelsea)
Lukaku finds his career at a crossroads after completing his loan spell at Inter Milan. It is not clear what Chelsea's plans are for the Belgium striker, while his fee and personal terms could block a permanent move to Inter.
Lukaku has been linked with AC Milan and Al-Hilal in Saudi Arabia.
Another loan move — possibly back to Inter — appears the best option if Chelsea is prepared sign off on another temporary deal.
Mason Mount (Chelsea)
Chelsea has already rejected a bid of about $51 million from United for Mount and two more have reportedly been submitted without success.
United's priority is to sign a top striker, while the Erik ten Hag could also be in the market for a goalkeeper, with David de Gea out of contract.
Mount is a versatile midfielder who can also play in a front three. The England international would add depth to United's squad ahead of the team's return to the Champions League next season.
Moises Caicedo (Brighton and Hove Albion)
Arsenal tried to sign Caicedo in January, but could not convince Brighton to sell.
Despite signing a new contract in March, Caicedo is expected to move this year, with Arsenal and Chelsea among the teams linked with him.
Rice appears to be Arsenal's midfield priority and it is not clear if manager Mikel Arteta will attempt to sign Caicedo in addition to the England international.
Randal Kolo Muani (Eintracht Frankfurt)
Some of Europe's biggest teams are being linked with Kolo Muani, a France forward who seems certain to be on the move.
Bayern is seen as one of the favorites to sign Kolo Muani as the German champions look for a replacement for Robert Lewandowski, who left last year.
PSG is another possibility, especially if Mbappe leaves.
Kolo Muani scored 23 goals and set up 17 more for Frankfurt last season.
Victor Osimhen (Napoli)
Napoli could see a number of its star players targeted following the departure of inspirational coach Luciano Spalletti.
Osimhen established himself as one of the most exciting strikers in the world as Napoli won the Serie A title and United, again, is said to be among his admirers.
Napoli may also have to fight off interest in Khvicha Kvaratskhelia and Kim Min-jae.
