(Reuters) - Leicester City's Shinji Okazaki is so drained when he returns from international duty with Japan he is barely recognizable from the bustling forward that played a key role in their title triumph last season, said manager Claudio Ranieri.
"I don't know what happens, but when he comes back he is a different person, believe me," Ranieri told British media. "He needs to recover. He is not a machine where you put in the money and he starts to run."
Okazaki featured in Japan's 2018 World Cup qualifying win over Iraq on Oct. 6 but did not play against Australia five days later.
The 30-year-old sat out Leicester's defeat to Chelsea on his return to England then came on as a late substitute in the Champions League before starting in their last two Premier League games against Crystal Palace and Tottenham Hotspur.
"There are players like Wes Morgan who go around the world but on the pitch he is the same," added Ranieri. "Shinji loses his energy. After the last international break it wasn't the true Shinji."
Okazaki played a key part in Leicester's title-winning season, scoring five goals in 36 league appearances.
Leicester are 11th in the league this season and have lost four of their 10 games -- more than they lost in the whole of last season.
They travel to Denmark to face FC Copenhagen in the Champions League on Wednesday before hosting West Bromwich Albion on Sunday.