Borussia Dortmund goalkeeper Roman Burki has said he is having trouble sleeping after the attack on the team bus last week.
The Federal Prosecutor's office in Germany is investigating after three explosions hit the team bus.
The attack happened as the players were driven to their home stadium for the Champions League match against Monaco, injuring defender Marc Bartra and causing the game to be postponed for 24 hours.
Monaco won the rearranged game 3-2 on Wednesday evening.
Switzerland international Burki, who had been sitting next to Bartra, said he had been unable to concentrate in the match.
He told Swiss newspaper Der Bund: "I still have problems sleeping.
"That's the worst thing, that I can't sleep through the night. When I wake up, I'm glad that I'm in bed at home."