Borussia Dortmund attacker Andre Schurrle admits teammates are baffled by Pierre-Emerick Aubameyang's decision to move to Arsenal.
Aubameyang is expected to join the Gunners this weekend.
"It's been a big issue in the team," said Schurrle after his team's 1-1 draw with Hertha Berlin on Friday evening. "It's caused unrest, and left us shaking our heads."
Schurrle filled in at number nine against Hertha after Aubameyang was left out of the squad for a second week in a row.
He continued: "It hasn't been easy to concentrate on football because there's only been one topic off the pitch.
"We've often tried to influence him in team meetings.
"When you talk to him, he's a great guy. Everything seems ok, but you never know what's going on in his head."