joins an impressive list of new recruits at Dortmund, who have also signed Julian Brandt, Thorgan Hazard and Hoffenheim defender Nico Schulz this summer.
had left Dortmund in 2016 as he joined Bayern Munich.
The move by 30-year-old Hummels
, who played 306 games and scored 25 goals for Dortmund from 2009 to 2016, was expected.
played 242 games at Borussia Dortmund alongside Klopp, winning two titles, including an historic double.
, whose father worked with Van Gaal during his two-year stint at Bayern Munich, was heavily linked with a move to the Reds following Van Gaal's appointment in 2014.
Bayern Munich star Hummels
spoke yesterday of his "strong bond" with the Northern Ireland fans whose support and fervour left a mark on Joachim Low's men at the Euro 2016 finals.
misses tonight's semi-final against France after picking up his second yellow card of the competition in the quarter-final shootout win over Italy.
In the unlikely event Wigan striker Grigg appears on the pitch at the Parc des Princes, Hummels
confirmed that, although he is not 'terrified' of him, he will be asking for the Northern Irishman's number nine jersey due to the social media buzz his chant has created.
Mkhitaryan's pinpoint cross, following a corner, allowed Hummels
to nod past Liverpool goalie Simon Mignolet.
, Sokratis and Ilkay Gundogan all took part in BVB's session just over 48 hours before the game at Westfalenstadion.
TEHRAN (FNA)- Manchester United are plotting a E70 million double raid on Borussia Dortmund, with Louis van Gaal keen to bring both Mats Hummels
and Ilkay Gundogan to Old Trafford this summer, according to the Daily Mail.
Dortmund: Borussia Dortmund are facing the prospect of losing a star player for the third year running with Germany defender Mats Hummels
waxing lyrical about a possible transfer abroad.