WATCH: Manchester United’s defence at sixes and sevens as they concede ugly opener to Dortmund

'Keeper should have done better, Antonio Valencia allowed Ousmane Dembele far too much space and the centre-halves were slow to react to the ball in the six yard box.

It's still early in the preseason so players can be excused for not being fully up to speed just yet. But Jose Mourinho will be demanding an awful lot more defensive solidity by the time Manchester United's Premier League opener rolls around. United took on Borussia Dortmund in Shanghai on Friday in the first game of the Chinese leg of their preseason tour. And they fell behind to a pretty sloppy goal in the first half when a Pierre-Emerick Aubameyang free kick was not dealt with properly by Sam Johnstone in the United goal. A scrappy series of play gave Dortmund their opener before, fifteen minutes later, Antonio Valencia conceded a penalty that was duly converted by Aubameyang. Marcos Rojo, who came on for Phil Jones at half-time, was put on his arse for Dortmund's third as Dembele turned him and rocketed an effort beyond Sergio Romero who also came on at the break. After clawing one back with a Henrikh Mkhitaryan tap-in, United let in a fourth after more defensive uncertainty as nobody closed down Gonzalo Castro who rounded out the scoring with a beautiful top-corner finish. Surely Mourinho will drill a bit more defensive concentration into his charges in the coming weeks.