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

If there were any doubters left, the Sporting striker's hat-trick in a 4-1 thrashing of Manchester City in the Champions League has surely silenced them once and for all.

The Sweden international has been prolific since moving to Lisbon in 2023 - he has scored 66 goals in 67 matches and 23 in only 17 this season.

"It's always nice to score and even better to score a hat-trick," he told Uefa after Tuesday's win. "You need to raise your level when you play better opponents. I tried to keep doing what I've been doing."

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.

"There will be a few clubs, including his current manager, who will be thinking that this guy can mix it with the best. It is surely a matter of time before the big clubs snap him up," former England winger Andros Townsend told BBC Radio 5 Live.

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 the Championship play-off final which turned out to be 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' permanent move in 2021 from Brighton to Coventry, 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. 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," Eklund 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.