German police have detained a suspect following Tuesday night's explosion near Borussia Dortmund's team bus.
The "Islamist" suspect is being held after three explosions detonated near the team bus as it was travelling to Signal Iduna Park for a Champions League quarter-final match against Monaco.
The game was called off and is scheduled to be played on Wednesday evening, while Dortmund defender Marc Bartra underwent surgery on a broken wrist after being the only person hurt in the blast.
A spokeswoman for Germany's federal state prosecutor in Karlsruhe, Frauke Koehler, said: "Two suspects from the Islamist spectrum have become the focus of our investigation. Both of their apartments were searched, and one of the two has been detained."
The police were investigating two letters found near the blast site that claimed responsibility for the attack.
The Chancellor of Germany, Angela Merkel, had earlier offered Dortmund words of encouragement after getting in touch with the club to express her support.
"Chancellor Angela Merkel got in touch with BVB CEO Hans-Joachim Watzke early Wednesday afternoon to offer her support," a brief statement on the club's official website reads.
"Merkel and Watzke discussed the situation in a lengthy phone conversation.
"The chancellor sees it as a positive sign that the team does not bow to terror and will play the match despite the difficult circumstances.
"She is continually staying up to date regarding the latest developments and keeps her fingers crossed for BVB on Wednesday evening."
Dortmund club president Reinhard Rauball provided a positive update on Bartra's surgery on Wednesday morning, telling n-tv: "We have heard that everything went well."
CEO Hans-Joachim Watzke also visited the team prior to their morning training session and issued a rallying cry to everyone associated with the club.
"I have just told the team in the dressing room to show society that we will not bow to terror," Watzke told the club's website.
"The BVB family was particularly strong when it had to cope with difficult situations.
"This is perhaps the most difficult situation we have had in the past decades and I am sure that we will show ourselves as BVB as strong and united as never before.
"We do not just play for us. We play for everyone. No matter whether Borussian, Bavarian or Schalke.
"We want to show that terror and hatred can never determine our actions. And of course we play for Marc Bartra, who wants to see his team win!
"We ask all BVB fans to support our team with full energy for 90 minutes."
In addition to Dortmund's rescheduled tie with Monaco, Wednesday will also see Atletico Madrid host Leicester City and Real Madrid head to Bayern Munich, with UEFA being moved to reconsider safety arrangements for the three games.
"While there has been no specific intelligence regarding any threat to tonight’s matches, we would like to assure teams, officials and supporters that UEFA always insists upon the highest standards of safety and security arrangements for competition matches, and that the safety of everyone attending UEFA's matches is our highest priority," read a statement from European football's governing body.
"Following last night's incident in Dortmund, UEFA - in co-operation with the police, security services, stadium management and the clubs involved - is reviewing the security arrangements for tonight's matches and security procedures will be enhanced accordingly wherever needed.
"We kindly ask all supporters to allow extra time for the possibility of enhanced security checks."