Jude Bellingham only turns 19 next June, but the England midfielder has already emerged as a leader on and off the pitch for Dortmund, where he shares a flat with his mum who keeps his feet firmly on the ground.
Mum's the word for Dortmund's rising England star Bellingham
Jude Bellingham has forged a potent partnership at Dortmund with Norway striker Erling Braut Haaland (R)
Bellingham is in his second season in Germany, but will be one of the first names in Dortmund's starting line-up against Sporting Lisbon on Tuesday in the Champions League.
"He's the most mature, most serious 18-year-old I've ever met," insists Dortmund's 2014 World Cup winner Mats Hummels.
"Jude is already one of the leaders, one of the loudest on the team.
"He's a great footballer and a great guy. He'll go his own way no doubt about it."
Exactly where Bellingham's future "way" lies is the subject of much UK media speculation.
His Dortmund contract runs until 2025, but Liverpool are reportedly at the front of a queue of Premier League clubs eager to sign the central midfielder who has been outstanding this season.
Dortmund sold Jadon Sancho to Manchester United for 85 million euros ($100 million) this summer in July and Bellingham is the latest talented Englishman the German club has developed into a potential Premier League star.
England manager Gareth Southgate saw enough to give Bellingham his international debut last November.
Signed from home-town club Birmingham City for 23 million euros as a raw 17-year-old last year, Bellingham has matured into one of the Bundesliga's best central midfielders.
"I'm sure we will see him in the Premier League in a few years," former Liverpool winger Steve McManaman wrote in an online column, predicting Bellingham is "going to be worth triple what Dortmund paid for him a year ago".
Bellingham scored a dazzling goal, then set up Erling Braut Haaland to score in a 2-1 win at Besiktas in Dortmund's opening Champions League game.
Bellingham planted a kiss on Haaland's cheek during a post-match interview and their fledgling partnership also produced goals in August's 3-2 win over Hoffenheim.
"It's crazy how good he is and he's only 18, three years youngers than me," enthused Haaland.
Dortmund coach Marco Rose is just as enthusiastic.
"Jude is a great boy," said Rose, who listed the midfielder's "mentality", "willingness to work" and "intensity" as his main assets.
Bellingham still has much to learn, such as when he allowed Moenchengladbach's Denis Zakaria to react fastest to a loose ball in the area to score in Dortmund's 1-0 away defeat on Saturday.
Without injured Haaland and club captain Marco Reus, Bellingham struggled to assert himself.
Off the pitch, Bellingham lives like any normal teenager.
During his four years at Dortmund, Sancho was regularly dropped for poor time-keeping.
Bellingham has his mum keeping a close eye as they share a Dortmund flat while his younger brother and father are back home in Birmingham.
Covid-19 travel restrictions meant the family were rarely together during the pandemic.
"We always said that one of us, either myself or Mark (Bellingham's father) would accompany him," Denise Bellingham told broadcaster DAZN.
"There isn't a day that goes by when you don't think it would be nice to be together as a family, but we always knew it was on the cards."
Bellingham says he "couldn't be more grateful" to have a parent living with him.
He claims not to suffer from pre-match nerves, but his mother has "butterflies eveytime I watch him. You worry about things, which is natural as a parent."
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