Arsenal’s defensive frailties were exposed once again, losing 3-2 to Borussia Dortmund in the Emirates Cup.

The Gunners, who conceded three goals in defeat to Real Betis in midweek, showed very little sign of improvement on Sunday afternoon as Joane Gadou scored what proved the decisive goal.

Bruno Guimaraes, signed from Newcastle for £75million on Saturday, was introduced to supporters inside the Emirates Stadium prior to kick-off before taking a seat in the stands to watch his new team-mates.

After a relatively even open exchange, Dortmund took the lead inside seven minutes when Samuele Inacio ran off Cristhian Mosquera in the box to latch onto a pass from Felix Nmecha and find the bottom corner.

Arsenal responded with some pressure of their own as Viktor Gyokeres smashed an effort against the crossbar, while Kai Havertz and Gabriel both came close to getting on the scoresheet.

However, it was the visitors that went in at the break with a two-goal lead thanks to a superb strike from summer signing Konstantinos Karetsas as he unleashed an unstoppable shot into the top corner.

Christos Tzolis lead the Arsenal second half fightback, first setting up Ethan Nwaneri and then winning the penalty for Gyokeres to score. On both occasions, those goals halved the deficit as Gadou punished some slack defending at a corner to net the winner.

Substitute Gabriel Martinelli did have a goal ruled out in stoppage-time for offside before a penalty shootout, as was planned before the match regardless of the result, took place after the match.

Arsenal won it 5-4 as Nwaneri lifted his spot-kick into the top corner to settle it after Mathis Albert was the only player to miss.