The German defender was candid in his post-match assessment, criticising the playing surface but insisting it would be a "stupid excuse" for Dortmund's underwhelming display.
"We were very, very weak with the ball. We were aiming for much better. No excuses about the conditions, even though the pitch was pretty terrible.
"The ball didn't even bounce properly. But those are all such stupid excuses. It was simply far too little today. We have to blame ourselves for that to some extent.
"I still think everyone is up for this challenge. We simply have to bring more to the table for the second game and work on it.
"We've shown over the last month or two that we're capable of playing better football - but that doesn't count here anymore."
Goalkeeper Gregor Kobel also voiced concerns, noting the ball "wasn't bouncing properly," as criticism of the pitch conditions came from multiple players involved in the tournament.
The issues on the field are just one part of a wider set of concerns surrounding FIFA's revamped Club World Cup.
Despite a year of promotional build-up, the tournament has been plagued by poor attendance. Organisers have been forced to slash ticket prices in an attempt to fill the stands, with little effect so far.
Real Madrid's preparations for their opening match at the FIFA Club World Cup have hit a potential setback, with Kylian Mbappe missing Tuesday's training session due to a fever.
Flamengo beat ES Tunis in Tuesday night's FIFA Club World Cup games, while Fluminense held Borussia Dortmund to a goalless draw.
Ex-Mamelodi Sundowns head coach Rulani Mokwena believes his former side are capable of holding their own at the FIFA Club World Cup in the United States later this month.
Jobe Bellingham could make a stunning debut for Borussia Dortmund in their FIFA Club World Cup opener against Fluminense, with reports suggesting the young star might start or feature early as a substitute.
