Jadon Sancho's departure could be reason for pessimism at Dortmund, but the club has been here before. A smart recruiting and blooding system means Gio Reyna is ready-made to help replace the England winger this season.
It's almost impossible to conceive how Borussia Dortmund can truly replace Jadon Sancho.
After bursting onto the Bundesliga scene aged 18, he notched up an incredible 114 goal involvements in just 137 matches during his time at the club.
But Dortmund aren't rookies when it comes to filling the void of departed stars and, in Giovanni Reyna, they already have a talented, versatile, and motivated youngster ready to step up his game.
After a whirlwind debut season, where he made 47 appearances, won the German Cup, and became a star of the US national team, the Bundesliga has only seen a glimpse of the 18-year-old's talents.
Now under Marco Rose, he looks set to play a big role in a new-look Dortmund team. And he's even been handed Sancho's old No.7 jersey.
"We talked about it from time to time last season," Reyna told Kicker magazine this week.
"He said that if he should leave the club, then I should wear his number. I can't thank him enough for what he did for me."
Club with a plan
Dortmund have rarely been caught unprepared when one of their attacking stars departs.
Mario Götze had his breakout season after Shinji Kagawa's departure in 2012, while there was a seamless transition from Robert Lewandowksi to Pierre-Emerick Aubameyang in 2014.
When Ousmane Dembele left in 2017, Christian Pulisic emerged. And when the American subsequently moved on to Chelsea, Sancho exploded.
Rarely do Dortmund require the transfer market to directly find a replacement, as they have a canny ability of circumventing any fallback by blooding young players early.
This time, Reyna will be the one expected to increase his attacking stats. And he looks primed to do so.
Motivated to improve
Reyna's seven goals and seven assists last season may not be too eye-catching, but he started the season as a wide-eyed 17-year-old.
He's bulked up in the off-season as his teenage body continues to adapt to the demands of professional football, and, under Rose's tutelage, he's been working hard to improve his overall game.
"I'm a player who thinks more offensively," he told Kicker.
"The defensive aspect was always a point where I had to improve. Now I have a coach who challenges me enormously in this area."
Reyna's versatility means he can fill Sancho's void on the wing, but he won't have to act as a direct replacement and can make his mark in the middle, too. By taking on more responsibiity in the front third, he'll also allow new signing Donyell Malen time to settle.
New dawn under Rose
It's a lot of pressure to expect such a young player to not only replicate an impressive debut season, but better it. Yet Reyna's off-season exploits with the US national team show he's growing into a leader despite his age.
A goal and an assist in a 3-2 victory over Mexico in the CONCACAF Nations League proved as much.
And his growing self-confidence means he sees himself playing a key role in Dortmund's new brand of football under Rose.
"Marco Rose has given us a clear plan," he said.
"We'll play high-octane football, according to the motto: 'go and get it.' We want to chase the ball, put the opponent under pressure, and attack together."
Sancho's goals and assists appear irreplaceable, but Dortmund's good track record and Reyna's continued rise gives hope that the loss won't be as damaging as first feared.