Tottenham Hotspur forward Son Heung-min has admitted to struggling to be fully prepared for action at the Asian Cup, as he prepares to head back to his club.
The 26-year-old was unable to help South Korea avoid a shock quarter-final loss at the hands of Qatar, having headed to the tournament on the back of a gruelling schedule of games for Spurs since the start on December.
And Son told the Japan times that he had not been able to adjust to the change of time zones and had been struggling to sleep at time.
He said: "I wasn't fully prepared. I felt physically empty.
"I would rather not speak about it really, but I haven't felt right physically. I was losing sleep and I should have looked after my condition better.
"I thought I would start to feel better and grow into the tournament, but it just didn't happen.
"Many people expected big things of us and I'm annoyed at myself for not being able to step up. I know I didn't perform well."
Spurs will hope that Son can recover as quickly as possible, with their star striker Harry Kane sidelined by an ankle injury and not expected to return to training until March at the earliest.
Tottenham are in FA Cup fourth round action on Sunday when they make the short trip to Selhurst Park to take on Crystal Palace.
Spurs are 8/1 to lift the FA Cup this season, with Manchester United available at 4/1 and Chelsea 5/1.
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