0:2 Monaco, Sven Bender with a bizarre own goal. Both goals came from Dortmund's unprotected right flank. Tuchel's idea was to play with a 3-man midfield, Dembele on the left and no one on the right, except for occasional raids by wing-back Ginter. This have backfired spectacularly as for both goals Lemar and than Raggi were in acres of space and with plenty of time to pick out the cross.
By 3-4 players out of position I mean Ginter is CB playing at right wing-back, Piszczek is a right wing-back (one of the best in Germany), for some reason playing at CB, Bender is a midfielder playing CB (probably forced by Bartra injury) and Dembele, while technically not out of position, is much more used to playing on the right, but he was moved to the left to accommodate Ginter, who once again is a CB playing at RWB. Sometimes a clever coach can be a curse.
Now he had to make 2 changes at half-time (Pulisic and Sahin for Schmelzer and Bender) which means yet another reshuffle.