BERLIN (Reuters) -Borussia Dortmund slumped to a 2-1 loss at Union Berlin in the Bundesliga on Saturday, only days after their 7-1 demolition of Celtic for their biggest European win.
Nuri Sahin's team had none of the aggression that earned them their record European win and despite pulling a goal back midway through the second half they struggled to create clear scoring chances.
"We had a weak start and apart from a few actions the entire first half was weak," coach Sahin, in his first season at Dortmund, said.
"At this level and in this stadium you need to be present from the start. If not you let in goals like the ones we let in. That cannot happen."
The defeat meant Dortmund dropped to seventh place in the standings on 10 points.
"Just before kickoff we made it clear what to expect here but we still gifted them the entire first half," Sahin said.
Union's Kevin Vogt ended a 10-year Bundesliga goal drought after converting a 26th-minute penalty. Vogt's previous goal was scored on Oct. 18, 2014, making it a record 275 Bundesliga matches between goals for an outfield player.
Dortmund were largely toothless up front, with Germany forward Karim Adeyemi, who scored a hat-trick against Celtic, out injured along with fellow forwards Julien Duranville and Gio Reyna.
They conceded another with Yorbe Vertessen's low strike from the edge of the box on the stroke of halftime.
Dortmund defender Julian Ryerson pulled a goal back for the visitors just past the hour but they could not find an equaliser despite late pressure.
(Reporting by Karolos GrohmannEditing by Christian Radnedge)
