ShareBorussia Dortmund were beaten by Bayer Leverkusen and Nico Schlotterbeck, 24 hours after signing a new contract, was booed by his own fans.The boos received by Nico Schlotterbeck during Borussia Dortmund's 1-0 defeat to Bayer Leverkusen have been described as "outrageous" by his livid centre-back partner Waldemar Anton.A stunning, 25-yard strike from Robert Andrich was enough to hand Leverkusen victory at Signal Iduna Park, halting BVB's four-match Bundesliga winning streak.Dortmund have now failed to win any of their last four home games against Leverkusen in all competitions, losing the last three in a row. On their own turf, it is the first time they have ever endured a four-match winless run or suffered three straight losses against the Werkself. And a miserable day for Niko Kovac's team was capped by Schlotterbeck being booed by sections of the home support, even after he signed a new contract on Friday.The centre-back put pen to paper on a new five-year deal after entering the final few months of his previous agreement, though reports in Germany suggested he has a release clause that applies to certain clubs, leaving some Dortmund fans disgruntled. When asked about the jeers by DAZN, Anton said: "No one deserves to be booed. Especially not here in our own stadium, that’s just unacceptable."It hurts us as a team, everyone in the stands needs to know that. I personally, and we as a team, can't accept it; it's outrageous!"Kovac echoed those sentiments, though he was also careful to avoid picking a fight with his club's fans as he said: "It should not be possible. "We are a team; we want to be successful. Of course, everyone should keep their disappointment to themselves. We want to stick together."One player who will be leaving Dortmund as a free agent at the end of the season is playmaker Julian Brandt, who has been linked with several of Europe's biggest clubs.Arsenal and Barcelona reportedly want Brandt, though the subject of staying in Germany – most likely with Bayern Munich – was put to him by Sky Sport after full-time."There are many ideas," Brandt said. "In principle, I'm not ruling anything out. But there are things I prefer, and there are things I currently find harder to imagine. "As I said, there are one or two ideas, but everything will happen in due course. You don't have to rush things. We are slowly approaching the end of the season, but we still have important games ahead."It would also not be fair to the club to suddenly start holding talks everywhere. You have to finish things properly, and then you have enough time to think about how things will continue. I am not worried about that at all."Borussia Dortmund were beaten by Bayer Leverkusen and Nico Schlotterbeck, 24 hours after signing a new contract, was booed by his own fans.The boos received by Nico Schlotterbeck during Borussia Dortmund's 1-0 defeat to Bayer Leverkusen have been described as "outrageous" by his livid centre-back partner Waldemar Anton.A stunning, 25-yard strike from Robert Andrich was enough to hand Leverkusen victory at Signal Iduna Park, halting BVB's four-match Bundesliga winning streak.Dortmund have now failed to win any of their last four home games against Leverkusen in all competitions, losing the last three in a row. On their own turf, it is the first time they have ever endured a four-match winless run or suffered three straight losses against the Werkself. And a miserable day for Niko Kovac's team was capped by Schlotterbeck being booed by sections of the home support, even after he signed a new contract on Friday.The centre-back put pen to paper on a new five-year deal after entering the final few months of his previous agreement, though reports in Germany suggested he has a release clause that applies to certain clubs, leaving some Dortmund fans disgruntled. When asked about the jeers by DAZN, Anton said: "No one deserves to be booed. Especially not here in our own stadium, that’s just unacceptable."It hurts us as a team, everyone in the stands needs to know that. I personally, and we as a team, can't accept it; it's outrageous!"Kovac echoed those sentiments, though he was also careful to avoid picking a fight with his club's fans as he said: "It should not be possible. "We are a team; we want to be successful. Of course, everyone should keep their disappointment to themselves. We want to stick together."One player who will be leaving Dortmund as a free agent at the end of the season is playmaker Julian Brandt, who has been linked with several of Europe's biggest clubs.Arsenal and Barcelona reportedly want Brandt, though the subject of staying in Germany – most likely with Bayern Munich – was put to him by Sky Sport after full-time."There are many ideas," Brandt said. "In principle, I'm not ruling anything out. But there are things I prefer, and there are things I currently find harder to imagine. "As I said, there are one or two ideas, but everything will happen in due course. You don't have to rush things. We are slowly approaching the end of the season, but we still have important games ahead."It would also not be fair to the club to suddenly start holding talks everywhere. You have to finish things properly, and then you have enough time to think about how things will continue. I am not worried about that at all."