Michael Tarnat believes Leroy Sane can become a star of Manchester City and the German national team if he maintains his recent improvement in the Premier League.
Sane moved to the English club from Schalke, having featured in Joachim Low's squad at Euro 2016, for a fee understood to be worth in the region of £37 million.
The 21-year-old winger initially struggled to adapt to life in Manchester, grasping for form and fitness, before scoring his first goal in City colours during December's 2-1 comeback win over Arsenal.
Manager Pep Guardiola has since acknowledged "something clicked" in that match and Sane netted in his next two appearances versus Tottenham and Crystal Palace.
Ex-Germany and Bayern Munich left-back Tarnat spent a season with City towards the end of his career in 2003-04 and has been impressed by Sane establishing himself as an integral part of Guardiola's forward line.
"Everybody looked at Leroy Sane last season in the Bundesliga," Tarnat told Omnisport. "He made great games for Schalke and then took the step to go to Manchester City, which is a great club where top players are playing.
"He certainly struggled at the beginning to adapt to the league and the players. That was something that he probably underestimated in the beginning.
"But in the last games he has acclimatised and will be an important part of Man City and also for Pep Guardiola.
"He is incredibly fast, has a good technique and a good finish. I believe these are all his strengths.
"If you are fast, have a good shot and score goals this is a good argument to become a top player, and I think that he will be maturing in a foreign country over the next few years.
"Foreign culture will make him a bit more mature from the point of view of personality. I think he will also be an important part of the German national team in the next years."
City face Monaco in the last-16 of the Champions League on Tuesday and lie second in the Premier League – a far cry from Tarnat's days in sky blue, when a side containing star names but short of youthful talent endured a brush with relegation.
"In my time we also had good players but I think we were all a bit past our best," he explained.
"We had Robbie Fowler, [Nicolas] Anelka, [Steve] McManaman and David Seaman as our goalkeeper, who was 39 years of age.
"Of course, now it's just that they have huge financial resources. With Pep Guardiola they will have a very, very powerful and successful team in the next few years as they will be playing a similar football as his previous teams.
"So I believe that Manchester City will also play a big role in global football in the next few years."