Some big names are available on a free transfer in summer 2020 from Europe's biggest clubs if they don't put pen to paper soon. Here are the top players, with the help of Transfermarkt.
Edinson Cavani (PSG)
The Uruguay striker was close to joining Atletico Madrid in the winter window, but PSG's demands for €20m scuppered the deal. Now he'll have his pick of clubs in the summer and will likely still choose Atleti, although they might have other plans to boost their strikeforce by then.
Now that the Callum Hudson-Odoi contract saga has finally been put to bed, Chelsea can turn their attentions to Willian and Pedro, whose deals are also expiring. The club need to act fast unless they want to lose them for nothing, though the feeling is that Willian will stay (amid interest from Barcelona and Juventus) and Pedro will leave, with a big-money forward like Jadon Sancho arriving in the summer.
Nemanja Matic (Man United)
Given how important Matic was to United under Jose Mourinho, it seems odd that Ole Gunnar Solskjaer has kept him out of favour. The Serbian is still only 31, but it's a case of whether United are more keen on youth than experience these days before they make a decision on whether or not to take up their one-year option on him.
Adam Lallana (Liverpool)
Liverpool's march to the Premier League title this season is happening without too much help from the former Southampton midfielder. In fact, he's been a bit-part player for the past few seasons but could play an important role at a smaller club as he's still only 31.
David Silva (Man City)
He may be 33, but Silva is still top quality and has already revealed that he will be departing after 10 years. City have another Silva -- Bernardo -- to replace him, as well as young Phil Foden, but the Spaniard will continue playing and told ESPN FC last year that he would like to end his career playing for Las Palmas, his hometown club on the island of Gran Canaria.
Tahith Chong (Man United)
Manchester United have been here before, with Paul Pogba. They have a talented young player who isn't getting game time in the first team and could let him depart on a free transfer, while another club (possibly Inter Milan in this case) snaps him up. Chong is 20 and frustrated, but the Dutch winger could be a bargain for a top European club if he doesn't move to Chinese Super League side Jiangsu Suning.
Dries Mertens (Napoli)
Napoli have a decision to make over Mertens, who is stalling over new terms with Manchester United and Chelsea having reportedly been interested in January. The future of another 32-year-old, Jose Callejon, is also up in the air as he turned down a move to Shanghai Shenhua in the summer.
Layvin Kurzawa and Thomas Meunier (PSG)
France left-back Kurzawa was linked with Arsenal and Juventus in January but expect those clubs to come back in for him if he's available for nothing. Juve wanted a swap deal to include Mattia De Sciglio, but that eventually fell apart, and Belgium right-back Meunier is another player that the Italian club could chase given their need for full-back reinforcements.
Mario Gotze (Dortmund)
Forever to be known as the man who scored the winner in the 2014 World Cup final for Germany, Gotze may feel like he has some more to prove. Still only 27 and after a failed move to Bayern, links to Liverpool (and former boss Jurgen Klopp) won't go away but there will be competition for his signature if he leaves Dortmund.
Blaise Matuidi (Juventus)
It's been surprising that more clubs haven't been linked with Matuidi given his contract situation and the fact he's still only 32. The Frenchman has actually started (19) more Serie A games than Cristiano Ronaldo (18) this season and would be a fine addition to any club wanting to strengthen their midfield.
Ryan Fraser (Bournemouth)
Bournemouth are reportedly ready to offer around £100,000 a week to winger Fraser to keep him at the club, but Arsenal and Leicester have shown an interest and his head has been turned. Both player and club have suffered from the speculation, with the 25-year-old stating recently that he was sorry for how it affected him.