Pierre-Emerick Aubameyang's transfer saga became a "burden" to Borussia Dortmund and has played a key role in their disappointing season, according to Ilkay Gundogan.
Germany midfielder Gundogan played with Aubameyang at Signal Iduna Park before joining Manchester City in 2016 and watched on from afar as the Gabon striker became Arsenal's club-record signing for £56 million on transfer deadline day.
The 28-year-old scored 13 goals in 16 Bundesliga games for Dortmund this season but, as their title challenge faded amid Peter Bosz's departure as head coach, Gundogan felt persistent speculation over Aubameyang's future proved an unwelcome sideshow.
"The whole hiccup was certainly not conducive to the performance of the team," he told Sport Bild.
"As a player, you see that and if you read negative things in the papers every day it's a burden."
Aubameyang joins a growing list of star names to have turned their back on Dortmund, along with Gundogan – who made his move to the Premier League ahead of Euro 2016 in somewhat more low-key fashion.
"I do not know if I could have done it the way Auba did," Gundogan added.