This time last year, Dusan Vlahovic was experiencing his first crisis of confidence.
Now, he is one of the most-coveted players in world football.
The reason for such a rapid and dramatic change in fortunes? A penalty.
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On December 16, 2020, Fiorentina welcomed Sassuolo to the Stadio Artemio Franchi.
At the time, Vlahovic was selected to start but had managed just one goal in his previous 10 Serie A appearances.
The kid who had once described himself as "the Belgrade Ibrahimovic" was racked by self-doubt.
However, when he converted a 35th-minute penalty, everything changed.
"It was like a breath of fresh air; it gave me life," he confessed. "From that moment, it became easier."
That's no exaggeration either.
That successful spot-kick proved a massive turning point in his young career, with Vlahovic closing out the year by scoring in three consecutive games, including a fine dinked finish in a 3-0 away win at Juventus.
In 2021, though, Vlahovic has gone to a whole other level.
Nobody mentioned the Serbian's name at the recent Ballon d'Or awards, while there was no place for him on the 23-strong FIFPro World XI shortlist either.
However, Vlahovic has undeniably been the game's breakout star of 2021.
He has hit 32 Serie A goals this year alone. Across Europe's 'Big Five' leagues, only the great Robert Lewandowski (42) has scored more.
What he's doing, at just 21, is literally historic. Only one player has scored more Serie A goals across a calendar year in the past 60 years: Cristiano Ronaldo.
The former Juventus striker hit 33 in 2020, yet Vlahovic still has two more games to surpass that tally.
Whether he does or not, though, Vlahovic will be the hottest property on the January transfer market.
Fiorentina, of course, would be loath to lose Serie A's capocannoniere [top scorer] halfway through the season.
The Viola are playing fantastic football under Vincenzo Italiano, who arrived from Spezia during the summer, and are presently fifth in the table.
European football is a legitimate target, but only if Vlahovic stays, and that's by no means certain.
The Serbia international's contract expires in the summer of 2023 and he has absolutely no intention of signing an extension.
Fiorentina, for their part, believe they have made Vlahovic a very generous offer and have no intention of bankrupting the club just to keep him.
"We made our proposal and it will not change," Viola director Joe Barone told Mediaset. "Both Dusan and his agents did not accept.
"People ought to have recognition for an environment that gave them so much. Our proposal increased and increased, but, at a certain point, we had to set a limit.
"This club used to have €90 million (£76m/$101m) revenue and now, after Covid-19 and various other issues, it’s around €72m (£61m/$81m), so we must take that into account.
"There are limits, there must be respect for the group and there are areas where Fiorentina simply cannot go."
And for the very same reason, the Viola would also be willing to let Vlahovic go.
As GOAL's Romeo Agresti revealed last month, Fiorentina have slapped an €80m (£68m/$90m) price tag on the hitman's head and are cautiously optimistic that they get even more than that, given a plethora of Premier League clubs are interested.
Arsenal and Tottenham are both keen, while Newcastle are now reportedly willing to pay up to €100m (£85m/$112m) for his services.
Then, there's Juventus, who would desperately love to sign him but are desperately short on money.
It's certainly easy to understand why Vlahovic is in demand. He is a player in sensational form and there is enormous scope for him to improve even further.
He's certainly determined to do just that. This is not a young player with a bad attitude or a poor work ethic.
Franck Ribery proved key in that regard.
During the Frenchman's time at Fiorentina, he would turn up two hours early to training. Such dedication and commitment to continued self-improvement had a profound effect on Vlahovic.
"If Ribery was doing that,” he told the Corriere dello Sport, “a guy that was nearly 38 and had won everything that a player could possibly win, how could I not, as a young guy that still had to prove himself?
"So, go and watch him, or stay in bed – it was a luxury I couldn't allow myself.”
The pair ended up becoming close, with Vlahovic revealing that he and his “big brother” would spend hours talking together, and not just about football.
"Right from the start, he gave me so much practical advice on the field, but he also helped me off it,” he explained.
"When my morale was low, he spoke to me, telling me not to give up. That was how I learned what it means to be a champion, both on the field and in life."
Vlahovic has been accused of cockiness but insists that he is only arrogant on the field, quite reasonably arguing that confidence is key for a striker.
He admitted in an interview with DAZN that, off the field, he is a little crazy, "but not in a bad way. I'm always shouting, joking and laughing."
The 21-year-old takes his development incredibly seriously, though, and studies other strikers, including Erling Haaland.
He has described the Norwegian as a “goal machine, a robot” but says that while the Borussia Dortmund ace is “certainly faster” than him, there is not much to choose between them in other aspects of the game.
That mix of humility and self-assuredness is evident in everything he does.
When Fiorentina hosted AC Milan last season, the former Partizan prodigy – who made GOAL’s 2017 NXGN list – waited outside the visiting dressing room for his idol, Zlatan Ibrahimovic.
The Swede gave Vlahovic his shirt, signed it and the pair took a photo together. Once again he was told: "Don’t give up."
When their two teams met again in Florence in November, Vlahovic decided to leave Ibrahimovic be after netting twice in a 4-3 win that ended Milan's unbeaten start to the Serie A season.
He explained to Telegraph.rs: "I know what it’s like to lose and I didn’t want to bother anyone."
It may have seemed insignificant but it offered further evidence of Vlahovic's maturity.
There was no hint of him suddenly feeling like the main man in Serie A now; that he believes has gone from a Zlatan fan to one of his peers.
"Every meeting with Milan is special for me, because everyone knows how I feel about Ibrahimovic," he added.
"But I do not feel that I am his successor as I have a very long way to go to reach his level.
"Just the fact he is still playing at the top level at the age of 40 says it all about his hunger and character."
Ibra's unwavering belief in his own ability is clearly a source of inspiration too, with Vlahovic feeling more sure of himself than ever before.
Almost a year after that crucial penalty, he will go up against Sassuolo again this weekend a very different player, in a very different frame of mind.
Now, the only doubt he has is over which top club he will join next.