In stifling conditions at the Notre Dame stadium in Indiana, the European champions faced the Bundesliga runners-up in what Jurgen Klopp had called "the first proper test" of his side's pre-season.
Missing veterans Roberto Firmino, Alisson, Mohamed Salah and Sadio Mane due to the Copa America and African Cup of Nations, Liverpool were hurt by a sloppy defence and Dortmund wasted no time in finding the net courtesy of a close-range strike from Paco Alcacer after just three minutes.
Harry Wilson found the net in the 35th minute to draw level but Dortmund scored two quick goals after the break.
Delaney made it 2-1 eight minutes into the second half with an easy tap-in and Bruun Larsen extended the lead after finding the bottom corner in the 58th minute.
Rhian Brewster converted a penalty in the 75th minute after Ben Woodburn was brought down in the box but the Reds could not find the equaliser in the closing stages in front of the 40,361-strong crowd.
Klopp had featured many of the younger players in his starting line-up but handed Trent Alexander-Arnold, Jordan Henderson, Andy Robertson, Virgil van Dijk and Georginio Wijnaldum their first summer match action after making 10 changes on the hour mark.
Liverpool will continue their pre-season tour with at Boston's Fenway Park against Sevilla on Sunday.
According to the BBC, Klopp said after the game against his former club: "You could see that Dortmund are a step further in their preparations but there was a lot of good things for us as well.
"How we conceded goals was a lack of organisation, but it is very difficult to have that at this stage.
"Really I learned nothing. But it is difficult when the ball isn't rolling. It was a tough night for both teams - it was really warm.
"I don't like what I see in a game in pre-season very often but there is always a reason for it. I am not over the moon with our performance but I know there is lots to come."
Follow Sporting Life on social media - find us on Facebook here or tweet @SportingLifeFC
Related football links
