Chelsea are no different and have until Monday, October 5 to finalise moves in and out of the club.
Frank Lampard will no doubt be looking to strengthen his squad for the season ahead after a tricky start to the campaign.
There could also be some exits too as players look for fresh starts elsewhere.
Here is a round-up of some of the latest Blues rumours doing the rounds.
PSG eye Bakayoko
French giants Paris Saint-Germain are weighing up a move for Tiemoue Bakayoko.
According to le10 Sport, sporting director Leonardo is keen on bringing the midfielder to the French capital.
He has previously worked with him at AC Milan.
The report states PSG have turned to Bakayoko having been frustrated in attempts to sign Sergej Milinkovic-Savic and Ismaël Bennacer.
Chelsea are said to want a €5m for the loan player, with a €40m option to buy inserted into the contract.
However, PSG are trying to reduce these figures to help push through a deal.
Rudiger future uncertain
Centre-back Antonio Rudiger is said to be ‘considering his future’ with Chelsea having been left out of the matchday squad for last Sunday’s game at Liverpool, report Sky Sports.
The Germany international, who was signed in 2017, has just under two years left on his contract at Stamford Bridge.
The 27-year-old is keen for first-team football to boost his chances of competing for his national side at next summer’s European Championships.
Rudiger also missed out on Chelsea’s opening game against Brighton, sparking talk of a possible exit.
The defender has played 115 games for the Blues so far.
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Hudson-Odoi linked with exit
Another player who could be heading for the exit door is midfielder Callum Hudson-Odoi.
The academy product has been told to seize his opportunity by boss Frank Lampard in Wednesday night’s League Cup game against Barnsley.
Hudson-Odoi has found game time limited to come by in recent weeks and could seek a move elsewhere to kick-start his career.
Lampard told the Guardian: “We have Christian Pulisic injured, Hakim Ziyech injured, we played Timo Werner out wide the other day, but the absolute natural winger who is fit is Callum.
“We need competition in those areas and players competing to make that position their own.
“That’s where Callum is at and why I keep saying he needs to show in training every day and when he gets his opportunity in games, which he will have against Barnsley.
“He has to show in every minute, on and off the ball, what he can do for the team. He’s had an early breakthrough in his career because of his talent, he’s had an injury and I want to see him flourish again.”