The 1.92 metre (6 feet four inch) centre back was a product of Bayern Munich's youth academy - he joined them at the age of six - but made his name by moving to Borussia Dortmund in 2009. He has won two German titles and Borussia were Champions League finalists in 2013.
Hummels and defensive partner Neven Subotic guided Dortmund to the Bundesliga's best defensive record when they conceded just 22 goals in winning the title in 2010-11. He has scored 25 goals in four seasons with Borussia.
ALL IN THE FAMILY
Football is a family business for Hummels. His father Hermann was a professional player and youth coordinator for Bayern Munich. His younger brother Jonas plays for third division German side Unterhaching. His mother Ulla Holthoff is a sports journalist who used to take the young Mats to her broadcasts.
Hummels, with his distinctive Musketeer beard, is now one of Europe's top centre-backs. According to British media, he is top of the defensive wanted list for new Manchester United manager Louis van Gaal and the English club have offered 20 million pounds (34 million dollars) for him. Barcelona have also been linked to the player. Hummel reportedly wants to stay in Germany for a while, but has said he would like to play for Manchester "some day".