Fabrizio Romano confirmed that Arsenal have made genuine contact with people close to Kostov and are considering a move, while Serbian outlet Sportinjo reported that the Gunners are on the verge of an agreement worth up to €20 million including add-ons — a figure that would represent a record sale for a Serbian club.
The International Centre for Sports Studies rated Kostov as the best Under-18 midfielder in the world based on his performances over the previous six months.
Kostov was still playing for Red Star's Under-19 side twelve months ago. This season he has accumulated more than 20 combined goals and assists for the senior squad, including a notable Europa League goal against Porto in October and a Panenka penalty against Barcelona in the UEFA Youth League the previous year. He made his senior Serbia debut against Albania in November.
The level of interest surrounding him is substantial. Barcelona, Bayern Munich, Borussia Dortmund, AC Milan, Paris Saint-Germain and Inter Milan have all been linked, with former Red Star manager and current Inter head coach Dejan Stanković's connection to the club presumed to give the Italian side an advantage in any competition. Arsenal's position, however, appears to be the most advanced.
Kostov is clear-eyed about his own assessment of his development.
"I don't think I've been so carried away by the fact that a lot is being written about my departure. All those big sums, 25 million euros — it doesn't affect my game or my stay here in any way."
He did, however, signal that he feels ready for a step up.
"I can't say the level is too easy because there are many experienced and really good players in the Super League. But of course I think I can play at a higher level. For sure. Right now I'm totally fine with this for me."
On where he would like to play, he expressed a preference for the Bundesliga or Serie A — a comment that adds a layer of nuance to Arsenal's reported progress. Red Star, who hold Kostov's contract until 2028, are in a strong negotiating position and have confirmed receiving offers exceeding €20 million.