Borussia Dortmund CEO Hans-Joachim Watzke has suggested April's attack on the club's team bus could have had some effect on their current crisis on the pitch.

Having won 19 points from their first seven matches this season, Dortmund have since collapsed and only picked up two points from their last six Bundesliga games, while they have already crashed out of the Champions League. In the 2-2 draw at Eintracht Frankfurt and Saturday's 4-4 draw against Schalke, they were on the wrong side of comebacks.

As Dortmund continue to back head coach Peter Bosz for now, Watzke has said that April's attack on the team bus could still have a negative effect on the team.

Three explosions rocked the team bus on April 11 as the players and staff travelled from their team hotel to the Westfalenstadion for their Champions League match against Monaco, which was postponed to the following day and Dortmund subsequently lost.

"We should not underestimate that it can still trigger post-traumatic stress months after it happened," Watzke said during his speech at the club's annual shareholders' meeting.