Mats Hummels to Manchester United: Player profile - who is the World Cup winner?
25-year-old centre-back is one of the world's best - but will Dortmund sell?
Bayern Munich will be regretting the day they allowed Mats Hummels to join Bundesliga rivals Borussia Dortmund.
Hummels, now 25, made just two appearances for Germany's most storied team before an impressive loan spell at Dortmund where he was eventually allowed to move for just €4m in February 2009.
Read more: Manchester United revive interest in Hummels
The 6ft 3in centre-back quickly established himself as first-choice next to the newly signed Neven Subotic, as Jurgen Klopp set about rebuilding a Dortmund side that had under-performed for years.
In his first full season in yellow, Hummels was a revelation. The club had the best defensive record in the league and eventually won the Bundesliga, their first title in nine years.
His great form continued the next season, as Dortmund posted the highest points total ever recorded in the Bundesliga (since beaten by Bayern) and won the DFB-Pokal Cup; Hummels scored in a 5-2 win over their rivals.
He has struggled with niggling injuries since that season and has played no more than 30 Bundesliga matches in the last two years - he was only fit enough to play 23 last season - as Bayern went on to win the title both seasons, as well as the Champions League.
However, despite the injury concerns he remains one of the best defenders in the world and again proved his class during the World Cup. Hummels was named to the Golden Ball shortlist after a brilliant World Cup
Hummels played in six of Germany's seven matches, scoring twice on the way to victory as well as being named in the 10-man the shortlist for the Golden Ball.
Strong in the tackle and powerful in the are, Hummels is able to read the game like a player who has been playing 10 years longer, stepping in to make interceptions and snuff out danger before it happens.
He is able to keep up with all but the very fastest of players and is comfortable on either foot - although he is right footed he usually plays on the left side with Subotic on the right.
He has a good range of passing and also likes to step into midfield with the ball, occasionally playing in a holding role for Klopp. His goals at the World Cup show he is a threat from set pieces and he has found the net 19 times since his move to Dortmund was made permanent. Hummels has grown to become one of the best defenders in the world at Borussia Dortmund
However, despite Louis van Gaal's obvious interest in Hummels, it is unclear whether he would want to move to Manchester United right now.
Dortmund aren't able to pay top wages - hence the departures of Mario Gotze and Robert Lewandowski in recent seasons - and United would be able to offer him a bumper deal.
But with United out of the Champions League and with Hummels approaching his prime, the defender may wish to spend another season in Europe's premier competition before assessing his options next summer. Dortmund won back-to-back titles with Hummels in the heart of their defence
Should Hummels decide to leave this summer United will face a fight, with Barcelona also said to be interested, especially after the retirement of long-serving skipper Carles Puyol and Gerard Pique's loss of form.
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