German champions Bayern Munich have confirmed the signing of Mats Hummels from Borussia Dortmund on Tuesday. The German defender has agreed a contract till 2021, although Bayern have yet to disclose the transfer fee.

TRANSFER COMPLETE! #FCBayern have also signed @matshummels, with the centre back agreeing a contract until 2021 too! pic.twitter.com/YShoT9dlL9

— FC Bayern English (@FCBayernEN) May 10, 2016

Earlier in the day, Bayern have announced a €35m signing for Portuguese midfielder Renato Sanches, who has signed a five deal with the Bavarians.

Sanches for €35m, Hummels for €35-38m. In one hour, Bayern have spent 33-38% more than the entire Bundesliga spent during the January window

— Clark Whitney (@Mr_Bundesliga) May 10, 2016

The 27-year-old defender started his professional football career with Bayern. After graduating from the club’s youth academy, he made his senior debut for the club in 2007. However, an unsuccessful spell at the club led to a loan move to Borussia Dortmund in 2008-09.

Hummels joined Dortmund on a permanent deal the following season and has spent nine seasons at the Signal Iduna Park. He has never looked back since. During his time at Dortmund, he won two league titles under Jurgen Klopp, and established himself as a regular member in the Germany national team.

Ancelotti hasn’t even arrived and Bayern already have Sanches and Hummels in. That’s how to operate

— James Ducker (@TelegraphDucker) May 10, 2016

This is not the first time Bayern have signed a player from Dortmund. They signed Mario Gotze from Dortmund in 2013, while Robert Lewandowski followed from the same club a year later on a free transfer.

Bayern’s defence will be strengthened following the arrival of Hummels, but it remains to be seen what impact it leaves on the overall competition of the Bundesliga.

Although Dortmund will receive a handsome transfer fee for selling Hummels, but it won’t be easy for them to replace a player of his quality.