Leroy Sane's career very nearly stopped before it really started.

In 2014 Sane was playing for Schalke 04's Under-19s team in the Uefa Youth League against Sporting, and it wasn't going well. Schalke were 2-0 down, and Sane was so poor that coach Norbert Elgert directed most of his half-time teamtalk at the winger.

“In the first half I wasn't content with him,” Elgert tells The Independent. “He was playing so badly, and his attitude and body language were so bad. I said at half-time 'This is your last match for my team.” That seemed to have the desired effect. In the second half, Sane ran the game, scored two (per video below) and Schalke won 3-2. “Afterwards I said to him “Ok, you can come back,” says Elgert.

A moment where things turn around rapidly seems to be a theme of Sane's still nascent career.

In his early days for Manchester City, after his £37million move from Germany in the summer, Sane looked like a rabbit in the headlights, a 20-year-old who'd taken on more than he could handle. He was overawed, the pace of the Premier League seemed too much for him. Pep Guardiola said he looked “scared” in those initial games. But at some point during City's 2-1 win over Arsenal in December, in which he scored, something clicked. Gabriel Jesus has attracted plenty of attention recently - deservedly, too - but over the last month or so Sane has been City's best performer.

After City's 2-0 win over Bournemouth last week, Guardiola's face lit up when asked about Sane. “The people say in the winter transfer window one guy arrived – Gabriel Jesus – but I think two people arrived,” he said, calling Sane, Gabriel Jesus and Raheem Sterling “the future” of Manchester City. He's been a fan for a while, too: when they were both in the Bundesliga, Guardiola congratulated the entire country of Germany for creating such an impressive player.

Sane is probably the forward that Guardiola would design in a lab. Lightning fast, aggressive both with and without the ball, a superb left-foot, direct and technically excellent. But perhaps the most impressive thing about him in recent weeks is his assurance on the ball, particularly when compared with how uncertain he looked in his early weeks with City. “He was always relaxed, very calm but with enough self-confidence,” says Elgert. “But I think that when a young player changes country to another league and playing style, it's totally normal he will need time.”

That said, Elgert doesn't think there was ever any doubt Sane would come good. “It was clear that after a short time of adaptation he would be successful,” he says. “England is no problem for him, because of his strength and speed. But his ability to repeat those sprints is ideal for this playing style too.” It's worth noting that Elgert's previous charges include Mesut Ozil, Manuel Neuer and Julian Draxler. You can probably trust his judgement on what makes a good young player.

Sane's physical gifts are genetic: his father Souleymane played 55 times for Senegal, while his mother, Regina Weber, won a bronze medal in rhythmic gymnastics at the 1984 Olympics. “I have the movements from my mother and speed from my father,” Sane said recently. So quick is he, that Elgert has said in the past that Sane could have been a sprinter if football hadn't worked out. “From the beginning he had good speed,” says Elgert now. “Good mobility, flexibility, and already a very good dribbler.”

The technical aspects took a bit more work, but came in time. Sane is a big fan of a nutmeg, but in his case it's not a way of showing off, just a pragmatic choice. “It’s not because I want to annoy the other player,” he said. “In my head it’s a way of going past a defender and that’s why I do it.”

Sane (r) has thrived working alongside playmakers Kevin De Bruyne (c) and David Silva (l) (Getty)

Despite only having been with City for a few months, he's already incredibly well liked within the club. He's smart and charming, a combination of a laid-back attitude off the pitch and a professional intensity on it, striking an ideal balance. It's perhaps for this reason that some of the older players have taken to him so much. Pablo Zabaleta is a fan, as is Yaya Toure, and those old pros have taken Sane under their collective wing. Much has been made of City's ageing squad, and while Guardiola has been trying to inject more youth into the playing staff, it's obviously something of which they're still conscious. Toure and Zabaleta, who could both be in their last seasons at the club, want to 'hand the baton' to a younger generation. Sane is perfect for that.

Sane has played almost exclusively on the left for City, but Guardiola is never shy about changing a player's role. “I think his best position may be a winger,” says Elgert, “but I'm sure that when he develops his vision and awareness on the pitch, I'm sure it would be possible to play No.10 – why not?” On that point, he could hardly have a better player to learn alongside, in David Silva, and Sane is paying attention. “He can see where everything is, he knows where to turn so that he has time,” he said of the Spaniard.