Jose Mourinho's men know that this game on Friday gives them the chance to express themselves against high-level competition and show what they can do ahead of the new season.
United come into the game on the back of a decent run out against Wigan Athletic wgere they won the game 2-0, but know that the games from now on in will be much harder.
Dortmund finished runners-up in the Bundesliga last season so will provide a tough test for the Reds with the talented squad they have at their disposal, in a game that should not be missed.
The Germans have played two pre-season matches so far, winning both, so they are further on in their preparations than United and the game is set to be a cracker.
Former players reunited
The game throws up some interesting encounters with former players playing against their former teams. Firstly, Henrikh Mkhitaryan - who signed for United from Dortmund earlier in the month - is likely to play some part in the game. Adnan Januzaj was on loan at Dortmund last season and set to see some game time.
Former Red Shinji Kagawa is in the Dortmund squad for the game after leaving the club to return to the Westfalenstadion for a second spell in 2014.
There have been six meeting between the sides in the past with the last coming in the 1997 Champions League semi-final, when Dortmund came out on top winning both legs 1-0 on their way to lifting the trophy. Overall though both sides have won three matches each so it couldn't be closer ahead of this game on Friday.
Mourinho has a full squad to pick from for the game and is set to give all of his players some minutes during this game. The England players who have joined up for the tour are not likely to play any part in the game as they need to train with the team for a couple of weeks before they are ready to play in a match.
Thomas Tuchel also has a full squad to choose from that he has selected for the tour with the main threat set to be in the form of in-form striker Pierre-Emerick Aubameyang. Tuchel will be hoping that his side can put up a great showing against United and show, even though they have lost a few players this season, they will be real contenders for trophies.