New-look Dortmund resume Bayern pursuit in German Bundesliga

Dortmund start their campaign at home to coach Thomas Tuchel's ex-club Mainz on Saturday.

But things looked bleak when captain Mats Hummels, then midfielder Ilkay Gundogan and Henrikh Mkhitaryan announced, one after the other, that they were leaving during the close season.

But no other German club was as busy in the transfer market, with Dortmund quickly re-investing the 89.5 million euros ($100m) they made in selling Hummels to Bayern, Gundogan to Manchester City and Mkhitaryan to Manchester United.

Bayern claimed a fourth straight German league title last season, finishing ten points clear of Dortmund, whose points haul of 78 would have given them the title in 49 of the 53 Bundesliga seasons to date.

Ottmar Hitzfeld, who coached both Bayern and Dortmund during his career, expects Tuchel's Borussia to give the Bavarians a run for their money again this season.

Both Bayern and Dortmund have qualified directly for the Champions League this season.

"I hope that Bayern won't single-handedly win the title," Hitzfeld told German radio.

"I am convinced: Dortmund will be serious competitors, they are chasing Bayern and have made very wise transfers."

The new signings include Germany forwards Andre Schuerrle and Mario Goetze, back at Dortmund after three years at Bayern where the World Cup winner was either blighted by injury or left on the bench by ex-Munich coach Pep Guardiola.

"I certainly didn't have easy year at Bayern. I want to play as many matches as possible here, to get the most out of myself, and help the team," said Goetze on his Dortmund return.

Having won the 2011 and 2012 Bundesliga titles with Dortmund, Goetze will be back in the black and yellow shirt with a point to prove.

"I believe the problem actually was that he wanted to work with Pep Guardiola more than go to the club (Bayern Munich) itself," Dortmund's CEO Hans-Joachim Watzke told Sport1 when asked about Goetze's Bayern sojourn.

Likewise, Schuerrle failed to win regular-starting places at either Chelsea, then Wolfsburg, for whom he scored nine goals in 14 league games at the end of last season.

- 'Performances, performances, performances' -

Dortmund's director of sport Michael Zorc said both Schuerrle and Goetze have the same task.

"At the end of the day, it's all about one thing for both of them: performances, performances, performances," Zorc told magazine Kicker.

"Neither Mario nor Andre have had top years, both aren't on an easy path and it's clear their performances will be in focus."

Barcelona centre-back Marc Bartra and left-back Raphael Guerrerio, who won the Euro 2016 title with Portugal, will bolster the defence, while tough-tackling midfielder Sebastian Rode has been recruited from Bayern.

French teenager Ousmane Dembele is an exciting prospect on the wing, as is Turkey international Emre Mor, who is also still only 19.

Spain Under-19 international Mikel Merino has also been bought from Osasuna.

At the helm last season, Tuchel was a resounding success as head coach after replacing Jurgen Klopp.

He overhauled the way Dortmund train, such as making defenders hold tennis balls in their hands during drills to break the habit of clutching an attacker's shirt.

Meanwhile, Dortmund's attack yielded 82 league goals last season, two more than even Bayern.

Central to this season's title challenge will be Gabon striker Pierre-Emerick Aubameyang, who scored 25 goals in 2015-16. 

Dortmund can expect near-fanatical support from the famous south terrace, which holds more than 20,000 home fans, and for the first time, Dortmund’s Signal Iduna Park enjoyed an average attendance of over 80,000 for Bundesliga games last season.

Their second league game, at RB Leipzig in a fortnight, means one of Germany's most traditional clubs will be the first to visit the fledgling outfit, heavily sponsored by energy drink manufacturer Red Bull, in Bundesliga history.