BERLIN • Mario Gotze had the nation at his feet when he netted the winning goal for Germany in the 2014 World Cup final. Fast forward nearly three years and Monday's news that the Borussia Dortmund star is sidelined indefinitely by a metabolism disorder is the latest blow to affect the attacking midfielder since the Brazil triumph.

Among the games he will miss is the Champions League round-of-16, second leg against Benfica next Wednesday, having lost the first leg 1-0 in Portugal.

"I am in the process of getting treatment and I will do everything I can to get back into training as quickly as possible," he told the club's website.

But there has been an air of frustration around the 24-year-old for weeks. He has scored just two goals in 16 appearances for Dortmund in all competitions after returning to his hometown club this season.

It has been a poor return on the €22 million (S$32.64 million) it cost the club to buy him back from Bayern Munich. Dortmund were forced to sell him for €37 million in 2013 when the Bavarian side triggered a release clause in his contract.

He has featured in only 11 Bundesliga matches this season, played the full 90 minutes just four times and spent six games as an unused substitute. He did not play last month after picking up a leg injury.

Dortmund coach Thomas Tuchel dropped him for Dortmund's Bundesliga win over second-placed RB Leipzig at the start last month because of poor form.

There has been external criticism, most notably from former Germany captain Lothar Matthaus, who believes Gotze is running out of options.

"If he does not sort it out at Dortmund, he has to go to China," Matthaus told Sport Bild. "Top clubs from abroad no longer have him on their list. He has to change. He doesn't have the speed, which is everything in football today."

AGENCE FRANCE-PRESSE