Bayern Munich have signed Renato Sanches from Benfica for an initial fee of €35million, and also announced the signing of Mats Hummels from Borussia Dortmund.

Sanches, 18, has agreed a five-year contract with the Bundesliga champions after completing a medical in Munich on Monday.

"Renato Sanches has been observed by FC Bayern over a long period," CEO Karl-Heinz Rummenigge said in a media release.

"We are fortunate to have him committed to our club in spite of well-known international competition."

Benfica later confirmed that the initial fee of €35m could rise to €80m, with an addition €45m depending on success-related bonuses.

Meanwhile, Bayern also confirmed Hummels would return to the club, agreeing a five-year contract with the Bundesliga champions and join on July 1 for an undisclosed fee, subject to a medical.

The 27-year-old appears set to captain BVB for one last time when Thomas Tuchel's side meet Bayern in the DFB-Pokal final on May 21.

Hummels told Dortmund's official website: "I have not made this decision easily after eight-and-a-half successful years at BVB.

"I was always proud and still am, to wear the BVB jersey and to be part of this exceptional team. Before I return to my hometown in the summer, we have a large, common goal all: once again to bring the DFB-Pokal to Dortmund.

"For that I will give everything just like my team-mates. I wholeheartedly thank my team-mates, all the staff and fans for this long and wonderful time in Black and Yellow."