Mauricio Pochettino has expressed concerns about this summer's new transfer deadline, stating foreign clubs will now have an advantage and that Premier League players could be unsettled if they are targeted when they cannot be replaced.
Tottenham and their English top-flight rivals have previously been able to sign players up until the end of August, but they must now complete their recruitment before 5 p.m. on Thursday, Aug. 9 -- two days before the start of the 2018-19 season.
The rest of Europe has not followed suit, however, so teams from abroad will have an extra three weeks to make additions to their squads.
Pochettino's concern is that an approach could be made for one of his players after Aug. 9, leaving Spurs with the difficult decision between selling when they cannot buy a replacement, or keeping an unhappy squad member.
"It will be a new experience for everyone because the transfer window is going to finish before the start of the season," said Pochettino. "No-one knows what will happen.
"I don't really agree [with the change]. I don't believe it is a good idea to finish the transfer market before Europe does.
"It is a massive advantage for the rest of Europe. We will see how it works but you have the risk that things will happen and it will be difficult for you to react. That will be a concern for everyone. Every single player is going to react in a different way.
"[Philippe] Coutinho was fantastic after the problem [with Barcelona last summer], but for Southampton it was a massive problem with [Virgil] van Dijk.
"I don't say that is a good example, but if some big club is going to try to sign somebody from our club, how are you going to manage the situation?
"If a club convinces your player and you don't allow him to go, how is he going to stay? On a good mental level or not? It is a situation which for sure in the next few years we need to fix. We need to have all of Europe with the same rules."
Leicester boss Claude Puel also raised concerns on Friday, saying a late raid for Riyad Mahrez could leave the Foxes stranded this summer, after they rejected late bids from Manchester City in January.
"In the summer there will be problems because some clubs will want players at the end of the market," Puel said. "It was the same thing in the winter with Riyad, it was just two days before the end of the transfer window. It was difficult to manage with a player who is perhaps angry, we cannot appreciate this situation.
"[The early closure of the window] is not a good thing. Of course all the managers want to start the season with the transfer window stopping but other countries can continue to buy players. Some players can be disturbed by this."
Pochettino, who will spend his summer in North London and Barcelona, already has transfer targets in mind. But he accepts Tottenham may need to be flexible, given they can be financially outgunned by wealthier rivals.
"We have some idea [what we want]," he said. "Of course we are working to deliver what is best for the team. It won't be easy but we are going to try. The number of players [available] will be limited, like every season, and the market today is going up. The last few seasons have become crazy, no?
"Sometimes we have priority players to sign, but maybe another club arrives with more money and you say 'ok, we need to find another option.' Sometimes you need to sign opportunities when you can't get your top priorities. To be sure it's complicated."
Looking back on the season, Pochettino feels there is great cause for celebration -- and he feels it would be oddly downbeat to focus on the club's lack of a trophy.
"You cannot finish with the feeling that it wasn't enough," he said. "A lot of amazing things happened. To beat Real Madrid, to finish top of our Champions League group when it was Dortmund and Madrid, to have amazing victories at Wembley against Madrid, Liverpool, Manchester United, nearly all the teams, to win at Stamford Bridge after 28 years, many amazing things happened. Sometimes I don't understand the negativity."
Meanwhile, Pochettino has warned Dele Alli to ensure he remains fully focused on his football and does not allow commercial activities to distract him. The 22-year-old midfielder has linked up with fashion brand boohooMAN to launch a clothing collection, with adverts being displayed all over London.
"He invited us to the launch but we couldn't go," said Pochettino. "I'm not worried. I understand that today life, football and business is completely different. I'm not worried if football is always his priority. The problem is if he starts to change the priorities of his life. For players, football must always be the priority -- football and family.
"I accept for some players family is more important than football, and if the balance is good it's not a problem, for sure. But if the priority becomes more business than football, I would be concerned and he should be too because that would be a massive problem.
"I never did adverts when I was a player. Nobody wanted to see me, I was very normal."