Legendary Sporting CP scouting director Aurélio Pereira passed away on Tuesday aged 77, the Portuguese club announced.
Responsible for Sporting's youth recruitment since 1988, Pereira brought teenagers Paulo Futre, Luis Figo and Cristiano Ronaldo to the Lisbon outfit.
All three eventually starred for Portugal while Figo and Ronaldo won the Ballon d'Or following moves to clubs abroad.
"He will forever be remembered as one of the greatest names in the history of national football and, above all, in the history of Sporting Clube de Portugal," a Sporting CP statement said of Pereira.
Ronaldo was just 12 years old when Pereira recruited him from Nacional's youth ranks in 1997.
He made his professional debut at Sporting CP in 2002 before moving to Manchester United after just one season.
Ronaldo, who has gone on to win 33 senior titles, captain Portugal to Euro 2016 glory and to the inaugural UEFA Nations League crown, paid tribute to Pereira.
The Al Nassr captain wrote on Instagram: "One of the greatest symbols of world youth training has left us, but his legacy will live on forever. I will never stop being grateful for everything he did for me and for so many other players. Until forever, Mr. Aurélio, thank you for everything. Rest in peace."
Sporting said Pereira was credited with discovering 10 players who were in the Portugal squad that won the 2016 European Championship in France.
He coached the club's youth squads for 20 years.
Portugal's Football Federation president Pedro Proença also mourned the loss of the legend.
"The death of Aurélio Pereira represents an irreparable loss for Portuguese football," Proença said.
"In addition to the enormous legacy built by the man who discovered some of the best players in our history ... We will have an enormous and eternal debt of gratitude to Aurélio Pereira and we will do everything to honor his legacy."
Information from The Associated Press was used in this report.