Having looked at Schalke 04 earlier, we now move to the other Ruhrpott powerhouse, Borussia Dortmund. After last winning the Bundesliga in 2012, Lucien Favre's men are looking to break FC Bayern München's six-year winning streak. We have a look at their top three summer signings.
Abdou Diallo (FSV Mainz 05, €28m)
While defending champions Bayern have kept control of their purse strings, Dortmund have splashed out the cash. Their biggest buy so far is 22 year old Frenchman Abdou Diallo, a 28 million Euro buy from FSV Mainz 05. The fee is just short of the club record of 30 million Euro, paid for André Schürrle in 2016.
With central defensive stalwart Sokratis moving to Arsenal, Diallo is the perfect replacement. Having joined Mainz from Monaco last season for just 5 million Euro, it constitutes an excellent piece of business for the Rhineland-Palatinate outfit.
Diallo has played eleven times for France's Under-21s, and the move to Dortmund is the perfect opportunity to take a big step in his burgeoning career.
Thomas Delaney (Werder Bremen, €20m)
Arguably Dortmund's signing of the summer. Danish international Thomas Delaney was a relative unknown when he joined Werder Bremen from FC Copenhagen in January 2017 for just 2 million Euro, but after an excellent spell at the Weserstadion he has shot up in value.
A versatile attacking midfielder with a keen eye for goal, Delaney hit the back of the net half a dozen times in 45 appearances for Werder, also notching up seven assists.
Delaney was also eligible to play for the United States due to his having an American grandfather, but he has collected 31 caps for the country of his birth. He has scored four goals in the red Danish shirt, including a hat-trick in a World Cup qualifier against Armenia. He also had a good World Cup, where his team reached the knockout stages, losing only on penalties to eventual finalists Croatia.
Axel Witsel (Tianjin Quanjian, 20m)
One of the more surprising transfer coups of the summer. After a year and a half in the Chinese Super League with Tianjin Quanjian, it looked as though Belgian international Axel Witsel was set to wind down his career.
Cue a solid World Cup with a Belgian team that finished in third place, and a return to Europe. The 20 million Euro fee is exactly the same as that paid by Tianjin Quanjian to Zenit Saint Petersburg in January 2017.
Tall, strong and powerful, the 29 year old Witsel will surely add steel to a Dortmund squad that has plenty of flair. He could be the final piece in the puzzle as Favre's men look to challenge for silverware.
For more Bundesliga fun stuff, check out my Little Bundesliga Book project. Copies of the 2016 pocket book are still available, with the aim of raising funds for a new edition at the end of this season.