Borussia Dortmund confirmed the signing of Germany defender Niklas Sule on a free transfer from rival and Bundesliga leader Bayern Munich for the next season on Monday.

"We are pleased that we were able to sign a German national player in Niklas Sule and retain him for four years," Dortmund sports director Michael Zorc said in a statement.

Bayern had already confirmed last month that Sule would leave at the end of the season when his contract expires having turned down an extension.

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Dortmund, which trails Bayern by nine points in the Bundesliga table, has pulled off a coupe by signing the towering 26-year-old centre back.

Sule has made 159 appearances for Bayern since it signed him from Hoffenheim in 2017 for 20 million euros ($22.5 million).

He is set to be a key player for Germany at the World Cup in Qatar, which kicks off in November.