Viktor Gyokeres has been proving people wrong since the very beginning of his career.

When the Sweden striker leads the line for Sporting against Manchester City in the Champions League on Tuesday, he will be the danger man. After all, since moving to Lisbon in 2023 he has scored 63 goals in 66 matches, and 20 in only 16 this season.

Rumours have been rife of a move to the Premier League, with Manchester United most heavily linked after Sporting manager Ruben Amorim’s move to Old Trafford was confirmed last week.

But Gyokeres, 26, has not always garnered such attention. It wasn’t until his time at Coventry City, where he spent two years, helping them to Championship the play-off final in his final match, that admirers circled.

Gyokeres began his career with IF Brommapojkarna in Sweden, leaving in 2017 before a spell with Brighton. He made only four appearances for the Seagulls and had time on loan at Swansea City, St Pauli in Germany and initially at Coventry. His talent, while evident, didn’t convince everyone.

“When I took him to Bromma, he was 14 and the head of the academy said he wasn’t good enough,” David Eklund, academy scout at Brommapojkarna, tells BBC Sport.

“I told him he will score goals. I first saw him when he was 11 years old and he was always a good striker. Shooting, heading and a great finisher; he had it all. When he was a teenager he got slower and stockier; he became stronger and more physical.

“He was never a superstar like Dejan Kulusevski [another Brommapojkarna youth product]. But he scored goals. That’s it.”

Strong self-belief, a desire to prove himself and a supportive family network gave Gyokeres the grounding to develop his game.

“He was a good person – always a good team-mate and with the coaches,” Eklund continues. “But when he got feedback he didn’t always take it well; he was headstrong. But after a couple of days he would go back to the coach and say they were right and he needed to work.

“He had a strong mentality but he’s a really nice guy. He always worked hard and had the idea of being a top player, training every day. He wanted to prove people wrong.

“Every single person has helped him reach a high level. His father was his coach at the grassroots level; he is a really good man. He helped Viktor a lot. When he moved to Brommapojkarna, his family were very important for him. He had a good, supportive environment.”

Gyokeres’ breakthrough into the first team at Brommapojkarna came as a teenager, and he soon became a key member of the team, scoring 20 goals in 56 games.

“They were struggling in the second division when he was 16, and the coach from the first team came to me when all of his strikers were injured,” Eklund continues.

“He said, ‘David, do you have any players who can play at that level now?’ I said, ‘I have Viktor. He is a good player; he’s strong enough to play with older players and he’s working hard.’

“Nobody at Bromma was thinking about him. It took time – maybe two or three months – but then he started to settle. The coach called me back and said, ‘wow’.”

Gyokeres’ move to Coventry in 2021, where he scored 39 goals, was a seminal moment. He became the main man for the Sky Blues and developed a great understanding with manager Mark Robins, who once again saw through initial scepticism.

“He first joined on loan for half a season and did OK, but not all fans were keen on his returning the following season,” BBC CWR’s Clive Eakin says. “But Mark Robins clearly saw something in his and bought him permanently.

“From then, it was clear he was something special. His ability to run at and through defenders [stood out]. Any time he collected the ball around the halfway line, you fancied his chances of going through to score. He has strength and is confident with his finishing.”

Premier League clubs were linked before Gyokeres joined Sporting. Instead, it was Manchester City-bound director Hugo Viana who seized the opportunity to sign him, and the Swede’s reputation has since soared.

Gyokeres’ recent rise has surprised even those where it all started. Eklund admits he never expected to see the striker reach the very top, but always backed him to be a success.

“In Brommapojkarna, he is seen as one of the best academy players,” he says.

“We have a lot of players playing at a high level in Europe, but nobody saw he would score goals at the highest level. I saw him playing in Sweden, Belgium or something. He has worked hard; his mindset is top.”

Eklund and Brommapojkarna have a track record of producing academy talent, with Kulusevski, John Guidetti and Albin Ekdal among other internationals to have emerged. He says that track record makes it easier to recruit the next generation.

“When I try to recruit strikers from other clubs, I always say about Dejan Kulusevski and Viktor Gyokeres. Brommapojkarna always produce good players, and we can use them as reference. Like, ‘look at him, Viktor Gyokeres is from Bromma’. It is a tradition, and players who come through think about those players. They want to have the same career as Viktor.”

Gyokeres has done things the hard way, railing against doubters throughout his career. Now he is one of the most prolific strikers in Europe, ready to take the next step on his journey.

Watch highlights of every Champions League game from 22:00 GMT on Wednesday on BBC iPlayer and the BBC Sport website and app.

There will also be a Champions League Match of the Day on BBC One at 22:40 on Wednesday.