Luka Jovic is set to be one of the main movers of this summer's transfer window, with the striker guaranteed not to be at parent club Benfica next season.
The prolific 21-year-old is currently second in the race for the Bundesliga top scorer trophy behind Robert Lewandowski, having netted 17 times in 26 games for Eintracht Frankfurt.
Jovic is currently on loan at the Commerzbank-Arena but the German club are poised to exercise their option to buy him outright for just €6 million (£5.3m/$6.8m).
Eintracht could then decide to make an instant and significant profit on the Serbia international by capitalising on interest from Europe's biggest clubs.
Indeed, with Barcelona, Real Madrid, Chelsea and Manchester City among those circling, they could get as much as €60m (£52m/$68m) for the striker.
Barca sent Eric Abidal, Pep Segura and Ramon Planes to watch him play against Inter in the Europa League and Jovic scored the only goal of the tie at San Siro.
Meanwhile, Real Madrid general manager Jose Angel Sanchez has held meetings with Jovic's agent Fali Ramadani, who also represents Juventus midfielder Miralem Pjanic.
The interest in Jovic is unsurprising as he is seen as one of the best young strikers in the world. As well as his excellent goalscoring record in the Bundesliga this season, he is also one of the top scorers in the Europa League with seven goals en route to the quarter-finals.
Defender Milos Veljkovic is familiar with Jovic from playing with him for Serbia and against him for Werder Bremen, and believes the striker can develop even further and play on the biggest stages of all.
"Luka has huge potential," Veljkovic told Goal. "I only know a few players who have such ability. He can do it with his right foot, his left and his head.
"The penalty area is his home, where he feels most comfortable. But I think he can improve even further. He is still very young. If he is willing to work on himself, he can do great things."
Despite only having played once for Serbia before last summer, head coach Mladen Krstajic brought him to the World Cup in Russia and then gave him his first international start in March this year, where he was rewarded with the opening goal against Germany.
His international manager also has high hopes for him, revealing that he reminds him of Barcelona and Uruguay superstar Luis Suarez.
"I wish him all the best and the greatest possible success, and it is clear that he has enormous potential. He can achieve great things," Krstajic told reporters.
"I would compare him to Luis Suarez, a classic striker with a good ball handling and a good understanding of the game. Dangerous at any time because he is always on the lookout for his chance. He takes advantage of even the slightest carelessness of his opponents."
Jovic would be the perfect addition to either Barcelona – where he would be the natural successor to the 32-year-old Suarez – or Real Madrid, where he could replace Karim Benzema.
Excellent with either foot, Jovic has a natural goalscoring instinct – as shown by his five-goal return against Fortuna Dusseldorf, which featured a 'perfect hat-trick' as he scored with both feet and his head.
Eintracht sporting director Fredi Bobic could be a busy man this summer fielding calls for Jovic, but as of now, no offers have been made and the former Germany international is optimistic he can keep him at the club.
"Soon we will pull the purchase option, which we have not done just for business reasons," Bobic explained to Welt.
"No offer for Luka has been made to us. We know that the player is being watched by the big clubs in Europe. That's fact. And it's also obvious that talks about the player take place in the background. That is normal.
"Due to his age and performance, Luka is currently the hottest product in Europe.
"I'm in regular contact with his agent. Nobody has made a move. We all, including Luka, focus on the final spurt. We can still achieve a lot. And Luka really feels like scoring goals in the Bundesliga and Europa League."
Jovic has echoed this statement, telling Sportbuzzer: "I'm honoured, of course, for such big clubs to show an interest in me. But right now I'm happy to be here in Frankfurt and I feel good here.
"At the moment I'm just concentrating on Eintracht Frankfurt; that's my top priority."
He may be happy at Eintracht Frankfurt for the moment, but with the likes of Barcelona and Real Madrid knocking on his door, Jovic will surely have his head turned in the very near future.