Tottenham head coach Mauricio Pochettino said striker Harry Kane could miss the start of next season if he plays for England at the Euro Under-21s Championship.
Kane, 21, has enjoyed a breakout season for Tottenham – scoring 20 Premier League goals for Pochettino's side.
He appears set to play for England at the Euro U21s Championship, which begin in the Czech Republic on June 17.
Pochettino said the striker could be sidelined for the start of 2015-16 if he played for England's U21s.
"Harry is not tired, but the problem is, if you play a lot of games in the Premier League and the Europa League over a season, you expend a lot of energy," he said.
"It is not easy but it is not about tiredness, it is about next season. We can see him in the future being the number one, not just for us but for the senior England team.
"I don't want to speak too much, but it is the FA's decision. I am sure they will take the right decision for Harry and all the players with England."
Despite his concerns, Pochettino said Kane would be part of the Tottenham squad to face a Malaysia XI and Sydney FC on May 27 and May 30 respectively.
"He deserves to go," he said.
"He will enjoy seeing a different country and it is one week to enjoy with our supporters in Australia and Malaysia so he deserves to go."
