Bayern Munich executive chairman Karl-Heinz Rummenigge and Carlo Ancelotti agreed Renato Sanches would be worth a potential €80million transfer fee in a March meeting.
During his time at Benfica, Sanches was heavily linked with a move to Manchester United, but Bayern swooped in to complete his signing for an initial €35m in May.
That fee could rise by a further €45m depending on success-related bonuses, but Rummenigge and Ancelotti felt the 18-year-old midfielder warranted such a risk.
The chairman pointed to Sanches' performances in Portugal's Euro 2016-winning campaign, where he was named Young Player of the Tournament, revelling in Bayern's astuteness to wrap up the deal ahead of any competitors.
"This is a tremendous amount of money, something we do not need to discuss, but I sat down with Carlo Ancelotti in March and we agreed: this player is worth the risk," Rummenigge told Bild.
"At the European Championship it has already been seen what tremendous power he brings, and what a personality he is on the pitch at 18. That's impressive.
"When Renato Sanches became known at the European Championships, he had already signed with us.
"We won [the race for his signature] because the others had just planned their holidays."
Bayern's Bundesliga rivals Borussia Dortmund have also spent big in the close-season, with big-money moves for Andre Schurrle and Mario Gotze adding to some other shrewd signings.
Dortmund have fought back from the brink of bankruptcy in the previous decade, and Rummenigge praised the work being done at Signal Iduna Park.
"I don't believe BVB getting into financial trouble will happen again. They have a good philosophy and will be our natural competitor," he added.
"It is no coincidence that Dortmund has continually established itself, and it is also proof that football is not exclusively about money, but also good work.
"The conditions were better at other locations, but in Dortmund they have worked better."
