UEFA president Aleksander Ceferin has supported the idea of closing next summer's transfer window before the 2018-19 Premier League campaign begins.
A vote is to be held later this week to determine whether to push ahead with plans to shut the market prior to a ball being kicked next term.
West Ham United vice chief Karren Brady recently claimed that the 'vast majority' of Premier League clubs will vote in favour of cutting the length of the window.
Ceferin is the latest to throw his weight behind the idea, telling The Times: "I am aware there are serious discussions around Europe regarding the shortening of the summer transfer window and we are following them closely.
"In my view, it is not good when footballers play for one club when the league starts and another club when the transfer window closes. There is a lot of uncertainty for a long time. Therefore I would say that the window might be too long and I would support it being shorter."
Fourteen votes are required from the 20 Premier League clubs to force the change, which will likely filter through to the English Football League.