The opening of the transfer window gives players opportunities to move on to pastures new, but for managers and clubs it can be a worrying time. The prospect of losing an important player to a bigger club with more financial clout must cause a few sleepless nights.
For example Neil Lennon must dread the phone call that tells him combative midfielder Victor Wanyama or top goal scorer Gary Hooper are leaving Celtic.
The pair have been in contract discussions for some time now and, as the January window progresses, without any sign of Hooper and Wanyama putting pen to paper, the chances of them leaving must increase.
There's no doubt both players have improved dramatically since joining Celtic and their stock has risen because of that.
Celtic's Champions league form in particular as a team and the players individually will have made other managers, especially in England, sit up and take notice.
It would be great if both players came out and stated they wanted to stay not just because of the upcoming Juventus games but for the long term as well, but it's been very quiet from both camps.
Loyalty is thin on the ground in football nowadays and that goes for both players and clubs as the modern game is dictated by money.
Having spent a lot of time in dressing rooms over my career, money plays a big part in where players play their football and not necessarily the club itself.
It's the single most talked about subject among players and with the English Premier League's record breaking TV deal starting next season the increased earning potential for Hooper and Wanyama will already have entered their heads.
From a footballing point of view it would make sense for both players to extend their stay at Celtic Park.
They'll be challenging for the league title every season and potentially appear in cup finals every year also.
Champions League participation on a regular basis is a possibility but I believe the final decision will come down to finance.
This is the world Celtic are in I'm afraid.
As big as the club are worldwide, coupled with the attraction of playing at Parkhead, they simply can't compete with the financial packages clubs in England's top flight can offer.
If I was still playing my head would have been turned as well and I fully see what is appealing to any player in a similar situation, football is a short career after all.
There's no doubt players hold the power nowadays, well the top ones do or the younger ones with potential which is the bracket both Hooper and Wanyama are in.
In general if players decide they want to move on there's little anyone can do to change their minds.
The dilemma managers are faced with is whether to keep an unhappy player which can upset the harmony of the team or sell them on for the betterment of everyone else. The majority of the time the player gets his wish and rightly the manager puts the team before an individual.
It's not just Celtic who are faced with this potential problem, it's an issue for managers and players around the world and I'm afraid it won't ever change because of the money on offer.
So as speculation and rumours build over the next few weeks some players will constantly check their mobile phones waiting for the call that could change their lives.
For managers, they can't wait until the February 1 so they can focus on football again and for supporters they are all hoping Lionel Messi fancies playing for their club!
They're allowed to dream I suppose, just like players.