Arsenal's global scouting operation is among the most envied throughout world football.
The Gunners' recruitment in recent years has seen more hits than misses and that looks set to continue with reports suggesting they're after one of the Europa League's youngest players this season.
Arsenal send scouts to watch Serbian wonderkid
The central midfield has been in inspired form this season with five goals and five assists in the Serbian Super Liga.
An attacking midfielder, Kostov recently made his senior international debut and does not turn 18 until the end of the season.
This means if Arsenal's interest is concrete, the teenager will not be able to sign this month but must wait until the summer, per Brexit regulations on players under the age of 18.
Bundesliga club Borussia Dortmund have also been credited with an interest by various outlets, indicating that the Gunners do not have a free run at landing the 17-year-old's signature.
In an interview with the Daily Mirror, Red Star Belgrade chief executive Zvezdan Terzic has claimed the club recently received an offer 'worth 20million (�17.45m)' for Kostov.
That represents a considerable outlay for most clubs in Europe, therefore it is most likely to be one of the continent's bigger teams that has supposedly formalised their interest.
Dubbed the 'Balkan Barella' due to playing style similarities with Inter Milan and Italy midfielder Nicolo Barella, it is alleged that Bayern Munich have also made contact with Red Star.
In FourFourTwo's opinion, Kostov looks to be the next big sale in Serbian football. The youngster is playing regularly and impacting games, therefore it won't be long before he moves up to a stronger European league.
Whether he is best placed moving to the Premier League straight away remains to be seen, however, clubs in England are likely to be able to offer the most lucrative contracts, which can prove tricky to turn down.
Whilst the Bundesliga probably serves as a better platform to take the next step in his development, moving to a Bayern or Dortmund, for example, might not yield the regular action Kostov requires to progress.
