The Tigers, who are now looking to step up their attacking recruitment following the departure of Keane Lewis-Potter to Brentford, are hoping to tie up a move for Estupinan in the next 24 hours.
Ghana international Benjamin Tetteh is also set to join the Tigers this week, however, it is not expected that he will be announced in time in order to link up with his teammates in Marbella.
The report claims that Hull owner Acun Ilicali is personally involved in one of the deals currently ongoing, however, it is unknown which one he is trying to get over the line.
Quiz: The big Hull City summer quiz – Can you score 30/30 without using Google?
Hull begin their new campaign in a little over two weeks, with Shota Arveladze striving to assemble a strong enough squad to cause problems in the Championship.
Of course, losing a player as influential as Keane Lewis-Potter will always come as a blow but it does present the Tigers with an opportunity to reinvest the hefty fee generated in several areas.
Forward recruitment has been a big priority at the MKM Stadium this summer, with a move for Estupinan an exciting prospect for Hull fans.
The Tigers would have wanted to complete the majority of their summer business earlier in the window, meaning it may take a while for the new additions to get up to speed with Arveladze’s demands.
It is an exciting time for the Tigers ahead of the new campaign, with Ilicali’s take-over allowing the Tigers to become more ambitious.