The first match of the Premier League season took place on Friday, 10 August - 26 days after the World Cup final.

"I think it's a lack of psychological freshness, rather than physical," said Southgate, whose team face Spain in the Nations League in Seville on Monday.

But he acknowledged it was a "complex scenario" for the "decision-makers".

And it is understood the Premier League feels it has very little room for manoeuvre because of the number of dates allotted to Fifa and Uefa competitions in the schedule.

Southgate, speaking at his pre-match news conference on Sunday, said: "A lot of teams haven't started yet at the level when they are at their maximum and there are a lot of injuries across our league.

"I don't really understand why our league started so early, but it did. It was a really difficult situation for the clubs.

"Look at Tottenham, who had so many players in the semi-finals of the World Cup. It is an impossible situation for the coaches."

Spain's La Liga and Italy's Serie A began the weekend after England's top flight, and Germany's Bundesliga on 24 August.

Southgate joked that the Premier League may not have envisaged England getting as far as the semi-finals.

"I hadn't looked into when the season started until we got back," he said. "Maybe they were expecting us to be back by the end of June.

"It's always easy to make a comment like that and not know the complex scenario the decision-makers had to go through, because that happens to me quite a lot."

England captain Harry Kane finished the World Cup as top scorer, but has since gone six games without a goal for his country.

Speaking after Friday's 0-0 draw with Croatia, the Tottenham forward dismissed suggestions he needs a rest, saying he does not think his "game has dipped".

Full-backs Luke Shaw and Danny Rose, central defender James Tarkowski and goalkeeper Alex McCarthy have been unavailable for England this month because of injury.

Thirty-seven Premier League players were still in Russia on the final weekend of the World Cup, featuring in the squads of the third-fourth play-off between Belgium and England and the final between France and Croatia.

Spurs had nine players involved that weekend, with seven from Manchester United and six from both Chelsea and Manchester City.