Manchester City are reportedly in advanced talks with Fluminense over a deal for Kayky.
The 17-year-old is yet to make his first-team debut for his Brazilian club, but the attacker's performances at youth level have allegedly led to a host of attention.
According to The Sun, Man City have been locked in discussions with both Fluminense and Kayky 'for months', and the Premier League outfit are now on the verge of sealing a deal.
The report claims that the Citizens could pay as much as £21.5m for the teenager due to various add-ons in the proposed agreement.
Pep Guardiola's side are also believed to be keeping a close eye on the development of fellow Fluminense youngster Metinho, who has played alongside Kayky for Brazil Under-17s.
Man City, meanwhile, are said to be keeping tabs on Borussia Monchengladbach's Denis Zakaria as they weigh up possible replacements for experienced midfielder Fernandinho.