Virgil van Dijk scored the only goal of an uneventful first half to send Liverpool into the break with the lead, but a string of half-time changes resulted in more action and ultimately saw Dortmund come from behind to win.
On Sunday, Karius was fortunate not to concede a goal in the first half when he rushed off his line to clear the ball, only for it to go straight towards Maximilian Philipp, who fired wide from long range.
He is, though, likely to be in goal for the two remaining matches of Liverpool's USA tour - against Manchester City in New Jersey on Wednesday and Manchester United in Ann Arbor on Saturday - and Karius received some backing from Spain goalkeeping legend Iker Casillas on social media. There are many more serious problems in the world, fuck!
"Will this attack [on] Loris Karius ever end?" the 37-year-old wrote on full-time at the Bank of America Stadium.
Simon Mignolet has been linked with a move away from the club, but it appears Karius is now the most likely goalkeeper to depart.
Coming three days after Liverpool sealed a world-record deal to sign his eventual replacement, Alisson, this will have compounded the German's issues. Leave the kid alone!
"To those who take joy in seeing other people fail or suffer, I feel for you", an Instagram post from Karius read. "He is also a person, as we all are!"
Liverpool's next pre-season friendly is against Manchester City at the Metlife Stadium in NY on Wednesday.