Huddersfield - Mauricio Pochettino is worried about Tottenham Hotspur's international players becoming burned out and injury-prone with the increasing demands being placed on them.
The Spurs head coach, who saw England captain Harry Kane score twice in a 2-0 win away to Huddersfield on Saturday, faces being without three key players for next week Champions League group match against Barcelona at Wembley.
Dele Alli will definitely be absent, while Jan Vertonghen and Moussa Dembele are now significant doubts for Wednesday's match against the Catalan giants.
Alli this week aggravated a hamstring injury initially sustained during England's UEFA Nations League loss to Spain on September 8, and Belgium internationals Vertonghen and Dembele were both withdrawn at half-time during the win at Huddersfield with muscle problems.
All three players were involved at the World Cup until mid-July, with Belgium beating England in the third-place play-off, and Pochettino believes they may have had insufficient rest before their Premier League season began on August 11.
The Argentinian manager has expressed particular concern over European football governing body UEFA's decision to add more competitive international games to the calendar by introducing the Nations League, arguing there is now less chance to rest players.
"The players finish the World Cup and they need to rest a few weeks," Pochettino said.
"Then they start the Premier League, and then there are the first international games. They play two games but they are not friendlies; instead, they play in the Nations League, and all the teams want the best players to play.
"Who cares about the player? It's so difficult.
"With the circumstances of the season, it's a massive challenge for everyone. It's not only us; there are a lot of teams that have the same problem.
"The players are not machines. You want to push and push and push them, and it's not easy. And no one helps, but we are warned before every single game to play the same players."
Alli's injury is of particular concern to Pochettino, because it appears to be an old problem that has resurfaced.
Asked how long the midfielder would be absent, the coach said: "I don't know. He reinjured the same muscle as with England against Spain, and that is the problem. It's important to be relaxed and calm."
Kane is another player who could claim to have suffered from such a busy schedule, having struggled for form since returning from the World Cup, where he was the leading scorer.
Tottenham's star striker scored 13 goals in eight games during September last year, but had managed just one in six before Saturday's visit to the John Smith's Stadium.
However, Kane showed signs his confidence and form are returning by scoring both goals against the Terriers, the first a header from Kieran Trippier's cross, the second a penalty after Florent Hadergjonaj was harshly ruled to have tugged Danny Rose back by the shirt.
Kane's return to scoring form secured a second successive Premier League victory for Tottenham, who have climbed back up to fourth place after recovering from the disappointment of defeats by Watford and Liverpool earlier in September.
"I am so pleased because the team was ready to fight," said Pochettino. "The ball was more in the air today than the grass, it was a massive fight.
"I'm sure it will be a completely different game on Wednesday (against Barcelona)."
Huddersfield are bottom of the Premier League, having managed only one league goal at home since February 11, but head coach David Wagner is confident they are playing well enough to move up the table.
"If you perform consistently as we've done and create opportunities, the reward will come," he said. "We have to focus on this and nothing else."