Right-back: Achraf Hakimi (Borussia Dortmund)
The marauding Moroccan was only a loan signing from Real Madrid; so, technically speaking, Borussia Dortmund never 'sold' Achraf Hakimi.
Dortmund couldn't meet Madrid's asking price to make Hakimi's move permanent, and the player went on to join Inter Milan in the summer. However, his impact in the two years he spent at the Westfalenstadion was such that it was impossible to leave him out of this lineup.
Dynamic, powerful and ingenious, Hakimi established himself as one of the best full-backs in Europe, with his creative ability adding a new dimension to Borussia Dortmund's attack. He made 17 assists and also scored 12 times in all competitions.
Centre-back: Sokratis Papastathopoulos (Arsenal)
After struggling to find a permanent address for several years, the Greek defender found his true home at the Westfalonstadion in 2013. For the next five years, he would be a constant presence at the heart of Borussia Dortmund's backline, making 198 appearances and helping his side to three titles.
Sokratis Papastathopoulos garnered acclaim for his leadership qualities and his penchant to win the ball without making a mistake. His defensive work-rate was phenomenal.
Arsenal saw him as the solution to their defensive woes, snapping him up for £17.6 million in 2018. Injuries aside, he has proved to be a bargain buy.
Centre-back: Matthias Ginter (Borussia Monchengladbach)
While at Borussia Dortmund, Matthias Ginter was nowhere near the starry centre-back that he is today at Monchengladbach, but that's more down to his mismanagement by the club.
Thomas Tuchel didn't entertain him too much, mostly calling him off the bench during the player's first two years at the club and also constantly moving him around on the pitch.
Despite making 42 appearances in his third and final season at the Westfalonstadion, Ginter moved to Gladbach for €17 million in 2017. He has since become a leader at the back with his organisational skills and versatility while also making his mark with Germany's national side too.
Left-back: Eric Durm (Eintracht Frankfurt)
Another position in this lineup that has a paucity of good options. We've opted to go with the only notable left-back sold by Borussia Dortmund recently: Eric Durm. The player now plies his trade with Dortmund's Bundesliga rivals Eintracht Frankfurt after a forgetful spell in the Premier League with Huddersfield in the 2018-19 season.
Durm was originally a striker, but Jurgen Klopp turned him into a full-back upon his arrival from Mainz, but the player failed to displace Marcel Schmelzer from the Borussia Dortmund starting XI and struggled for regular football.
Despite several injury issues plaguing him during his stint with the club, Durm made 97 appearances in four seasons, scoring twice and laying 11 assists.