Manchester City boss Pep Guardiola was left angry with Borussia Dortmund's tactics for their friendly defeat in the International Cup.
Debutant Riyad Mahrez and Lukas Nmecha were chopped down and Dortmund had two players booked by referee Armando Villarreal.
Guardiola complained last season about a lack of protection from referees for his players and was worried by Dortmund's approach.
“That's why there's a referee," said the City boss. “It's their job.
“Yeah, I'm worried, but it is what it is. We try to play with it. In some minutes we started good and after we that had a few problems.
“We missed the ball in some situations and they used the counter-attack."
Joe Hart replaced Claudio Bravo at half-time at Soldier Field for Guardiola's young side and the Catalan was pleased with his solid display.
Guardiola said: “We have four goalkeepers.
“We decided today on Claudio and Joe. In spite of the decision nobody can doubt his quality as a goalkeeper and what he has done in the last 10 to 12 years.
“We're looking to decide if he's going to stay or leave and we will see at the end of pre-season."