Sami Mokbel of MailOnline wrote the Primeira Liga prospect has earned comparisons to David Silva, and alleged admirers City could view Chaves' gem as a potential successor to the Spaniard, who turns 33 in January.
However, Eustaquio sees himself more in the mould of Barca anchor Sergio Busquets, and Mokbel provided quotes from the 21-year-old, who has said: "I think there is no smarter player in the field than Sergio Busquets, so I look at him when I occupy the position of No 6, half defensive."
Eustaquio has quickly adapted to playing in Portugal's top flight since joining Chaves in January, and his form over the past year has been rewarded with seven caps for Portugal's under-21 team.
Portuguese football expert Jan Hagen predicted at the time of his arrival from second-tier Leixoes that Eustaquio would prove to be a high-value signing:
Jan Fredrik Hagen @PortuBall
Official: On deadline day, Chaves make their first(and probably only) piece of business in this window by signing Leixões' Portuguese U21 international Stephen Eustáquio. The 21-year-old midfielder joins on a 4,5-year deal. At €500k, it could turn out a real steal. https://t.co/8R82W1vwvB
That will be true if a club decides to trigger his release, and both City and Barcelona will likely consider his £13.3 million cost to be well within their spending range.
However, Sporting CP are understood to have already lodged an offer for the player and could be ahead of the queue to offer him his next step in Portugal.
Eustaquio was born in Leamington, Canada, to Portuguese parents and moved back to their homeland at a young age. His contract with Chaves doesn't expire for another three-and-a-half years, meaning the club has little reason to settle for a price lower than that stipulated in his contract.
Any younger stars who have found success at City have mostly arrived for large fees, and Eustaquio may not like the look of attempting to crack the star-studded midfield assembled by Pep Guardiola.
Barcelona's senior squad may be no easier to break into, but the Catalan powerhouse holds some renown for offering the youth their opportunities at the Camp Nou and the player has stated his admiration for Busquets.