Teams can talk to these big-name free agents from January 1

Kylian Mbappe of Paris Saint-Germain. /CFP

The winter transfer window of European football opened on Saturday, meaning that teams will be able to reach out to players who will become free agents in half a year for negotiation.

Kylian Mbappe of Paris Saint-Germain (PSG) is the biggest name among these players. He is set to become a free agent after turning down multiple contract extension offers by the French giants. Neither he nor Real Madrid ever tried to hide their passion for joining hands. Real are at the entrance of building the next Galacticos. No one makes the better option than 23-year-old Mbappe for its announcement.

Before any deal is reached, Real and Paris are meeting in the UEFA Champions League Round of 16 competitions in February.

Paul Pogba of Manchester United. /CFP

Despite his deteriorating reputation at Old Trafford in recent years, Paul Pogba of Manchester United is likely to be another game-changer free agent.

In 2016, the Red Devils were desperate enough to pay 105 million euros (about $119.4 million) to land him from Juventus. That's a very intimidating cost to fix Man United's mistake of letting Pogba leave for nothing in 2012.

This time, the English powerhouse may again let him depart for not even a penny again because that's how desperate they wanted him to go. It took the two sides about three years for their relationship to sour. Whatever Pogba did or said seemed to be wrong in the club's eyes and vice versa.

Despite all the reports about how unprofessional Pogba has been, he's still the midfield engine of World Cup champions France. Theoretically, he can still make decent contributions for a team if they can keep him happy.

Antonio Rudiger of Chelsea. /CFP

Chelsea, which recently seemed to be dropping off the title competitions in the Premier League, are looking at possible departures of multiple key members, including Antonio Rudiger, Cesar Azpilicueta and Andreas Christensen.

Rudiger has been performing well at Stamford Bridge, and he said he's "happy" in Chelsea. However, it just kept feeding speculations that the club has not signed a new deal with him. A world-class defender like him is on the radar of other heavyweights like Real, Bayern Munich and PSG.

Cesar Azpilicueta of Chelsea. /CFP

Azpilicueta is in the similar situation with Rudiger. He said "everything will take care of itself," when asked about his contract situation. The 32-year-old veteran has been one of the favorites of Barcelona's new manager Xavi Hernández. The Spanish club is looking to bring both Azpilicueta and Christensen to Camp Nou to lead their young squad.

Chelsea's great performance in the past year came from their incredible depth of squad, which also led to a challenge. Though they are competing in multiple events, the club won't be able to give all of their players enough time on the field. Furthermore, losing any of the above may cost Chelsea a lot to fill in their absence.

Gareth Bale of Real Madrid. /CFP

Real, which have been in the center of different transfer and signing speculations, have their own issues to deal with, and two of them are about veterans, Gareth Bale and Luka Modric.

One may be surprised to learn that it has been nine years since Bale arrived at Santiago Bernabeu at a record price of 101 million euros (about $114.9 million). He has scored 106 goals in 254 games for Real and made key contributions for the team on many key occasions, including winning the Champions League title in 2018.

Nonetheless, Bale and Real have been pointing fingers at each other for years, and neither side seems willing to back off. "It's not important, I don't care what they think. I don't care about them [Real Madrid fans]. Why should I care? I think the fans treated him disgustingly." Bale's agent Jonathan Barnett said in November 2021.

Bale proved himself useful as long as he was given a chance to perform in Tottenham Hotspur in 2020. Part of the reason he failed to stay was his high salary. If he becomes a free agent, salary can be negotiated, especially for a 32-year-old.

Luka Modric of Real Madrid. /CFP

Modric's situation is different from that of Bale. Real, both the club and fans still love him. He has been playing an integral role in the team's midfield as well. However, it has been Real's tradition to ditch old guys when they are landing a new generation of super stars. The arrivals of new owners of Santiago Bernabeu may not only lead to cut in Modric's time on the field, but also force him to change the way he plays.

Fleeing from being marginalized does not sound too bad, especially when there are other clubs like Inter Milan interested in bringing in 36-year-old Modric.