The 21-year-old became the most expensive transfer in British football history when he secured a £107m switch to Chelsea on Monday after month-long negotiations between the clubs.
Advertisement
The Blues were alerted to Fernandez's superb displays during Argentina's run to World Cup glory in Qatar and quickly made him their no.1 transfer target.
Benfica had been reluctant to sell the star who only joined the Portuguese giants last summer from River Plate.
But Chelsea's persistence proved too much for Fernandez who made his intentions clear about moving to west London.
Advertisement
Costa granted Fernandez his wish of playing in the Premier League as Benfica prepared for their league game against Arouca on Tuesday evening and explained he did not want to keep an unmotivated player.
"Enzo Fernandez did not want to stay at Benfica. He didn't give us any chance," said the Benfica president.
"I did my best, I'm sad, but I'm not going to cry for a player who didn't want to stay. When Chelsea arrived, it was really impossible to change his mind."
Advertisement
Advertisement
Costa continued: "During deadline day we found an agreement to sell Enzo to Chelsea in the summer but he didn't want to stay.
"From the moment Enzo realised [Chelsea were going to pay] the value of the clause it was unrelenting. We tried to insist, but the player did not show any openness to continuing at Benfica.
"I proposed to Chelsea that he stay until the summer for a lower value, but the player did not want to continue at Benfica - and this is when everything changed."
Meanwhile, Fernandez's former club River Plate are set to receive a huge cash windfall after they inserted a 25 percent sell-out clause in the deal that took Fernandez to Benfica.
Advertisement
The Argentinian side will cop a whopping £26.75m fee for the World Cup winning midfielder.