Borussia Dortmund coach Jurgen Klopp has said his side must improve drastically for Wednesday\'s UEFA Champions League clash at home to Real Madrid in the wake of their Ruhr derby defeat. Dortmund were humbled 2-1 at their own Signal Iduna Park stadium by neighbours Schalke on Saturday as they lost the Ruhr derby, leaving them with just one win in their last six games in all competitions. Real are top of Group D with two wins against both Manchester City and Ajax, and Klopp says Dortmund must improve greatly on their performance against Schalke if they are going to trouble the Spanish giants. Everything has to be better, we must tick off the Schalke game and next time just show what we can do. Jurgen Klopp, Borussia Dortmund coach \"Everything has to be better, we must tick off the Schalke game and next time just show what we can do,\" said Klopp with his side fourth in the Bundesliga and 12 points adrift of leaders Bayern Munich. Klopp has injury concerns too, with midfielder Jakub Blaszczykowski definitely out, but defender Marcel Schmelzer, plus midfielders Mario Gotze and Ilkay Gundogan could be fit in time to face Real. \"Jakub Blaszczykowski will not be ready in time, whether the other three are available again, I do not know yet. Each day helps,\" said Klopp. Formation switch \'didn\'t work\'With so many injuries, Klopp switched to a 4-4-2 formation against Schalke, with Poland striker Robert Lewandowski and Germany star Marco Reus up front. But the move backfired as Schalke took an early lead and Klopp admitted his error. \"I put my hand up to that,\" he said. \"I only wanted to improve the formation, but it didn\'t work and I have to accept that. We are capable of playing much better. \"We have been playing really good football recently, sometimes even better than last season, but we didn\'t do enough against Schalke and it wasn\'t just about the four injuries.\" From Fifa