DORTMUND, Germany -- Peter Bosz insisted Borussia Dortmund are "not lacking stamina" after a 2-1 loss at home to Tottenham Hotspur on Tuesday night.
Borussia Dortmund were deserved 1-0 leaders at half-time thanks to an opener by Pierre-Emerick Aubameyang in the 31st minute. Though the hosts could only hold onto their slim advantage until the 49th minute as Harry Kane pounced on a chain of individual errors in Dortmund's backline.
After conceding the equaliser, the Black and Yellows could not find a way back into the game, looking abject until full time. Tottenham midfielder Son Heung-Min scored the winner in the 76th minute, ensuring that Dortmund would remain winless after five matches in the Champions League Group stage.
Asked whether his team lacked the physical edge after not showing a fight to get back into the game in the second half, Bosz told his news conference: "You could see after the 1-1 that we are lacking confidence.
"In the first half we played well. We were well-organised and created chances. After the equaliser, we couldn't carry on, though. Stamina, however, is not an issue for us."
Team captain Marcel Schmelzer agreed with his head coach, telling ESPN FC after the match: "We need to stop the individual mistakes. It was very harsh that [Tottenham] immediately took advantage of our errors. It is especially difficult for our younger players to deal with those mistakes.
"Though I wouldn't say that we are lacking leaders on the field or do not have the necessary stamina. Right now, it is all down to confidence for us.
"Everything was going well for us [until the equaliser], we were in the game and took the lead. We gave up a lot of cheap goals in recent games so conceding again today was another mental setback. Overall, though, we managed to work on our weaknesses. Now we just have to make sure to avoid individual mistakes."
Tuesday's match in the Champions League did not provide the much-needed confidence boost for the Westphalians, who will host second-placed Ruhr Rivals Schalke in the Revierderby on Saturday.
After one draw and four losses in the last five league matches, the pressure is rising on the team that plummeted from first to fifth place in the Bundesliga table during the same timeframe.
Asked whether a loss in the crucial derby would seal his fate as BVB head coach, Bosz answered: "I wouldn't say that, but I'm well aware that as a Dortmund coach you need to deliver results and that the pressure is mounting when you don't. Obviously, the derby is very important in that regard.
"I think the derby is maybe the best thing that can happen to us right now. Maybe we don't need a psychologist [to rebuild confidence] but the game will do that by itself."
Christian Pulisic was not part of the squad on Tuesday night due to muscular problems, though Bosz was hopeful that their key player can return to give his team a boost on Saturday: "He trained individually [on Tuesday]. I'm not sure that he will return, but I'm hopeful."