Michael Ballack has revealed that he has been hugely impressed by Manchester City's Leroy Sane, and his improvement under Pep Guardiola.
The 21-year-old made a £40 million move from Schalke to City last summer but he has only recently started to establish himself as a key player at the Etihad Stadium.
His good form with City led to starts in both of Germany's international fixtures against England and Azerbaijan, while he also scored against Arsenal at the weekend ahead of his side's trip to Chelsea on Wednesday.
Ballack is a former Germany captain and won 98 caps, and he believes that Sane will become a key player for club and country.
"I am impressed by his physical improvements since he changed club, as he was just a young kid from Schalke," Ballack, speaking on behalf of BT Sport to Goal. "He adapted quickly to the Premier League and he has this confidence to go dribbling, he's open to face defenders.
"Sometimes he gets knocks but he stands up and is not hiding. He is asking them questions again, not scared of the challenge. He has improved his game so much, because of his physical ability to make long runs. Sometimes he will play full-back, wing-back or on the wing.
"I've seen fantastic games when he has been more defensive and made his long runs forward with the ball and without the ball. His vision on the ball [is great]. his left foot, he has a great touch and I am sure with Pep Guardiola as a coach, he will learn and learn and learn more as he grows in age.
"He has shown that with the national team as well when he played in the last months. He was quality, not nervous and performed immediately. I am pretty sure he will be one of the key players in the future for Germany."
Manchester City were Ballack's pick to win the Premier League earlier in the season but they have since fallen away as Chelsea went on a 13-game winning streak to open up a healthy lead in the league.
Ballack believes that City's prospects of the title have slipped away following their 2-2 draw at Arsenal, but that Guardiola will one day win the Premier League.
"I didn't expect Chelsea would come back so quick and so strong after a difficult season," admitted Ballack when referring back to his title prediction. "I thought Man City is the team that you have to beat [to win the title] this year.
"Sometimes a new coach can find it not easy. A long season with the Champions League, things change, a different style of football and the team has to adapt to the coach as well.
"Sometimes it works well [like with Chelsea], sometimes it is not so quick [with City]. I am sure he has the quality and Man City has the quality to win the league next year."
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