Ilkay Gundogan has admitted that rival managers Pep Guardiola and Jurgen Klopp are both as intense as each other during training sessions.
The two managers took the Premier League title race to the final day last season, with Manchester City finishing one point ahead of Liverpool, despite the latter claiming a club-record 97 points.
Gundogan played under Klopp during the pair's time at Borussia Dortmund ahead of moving to the Etihad in the summer of 2016, when Guardiola took over from Manuel Pellegrini and made the German one of his first signings as City boss.
Reflecting on what it was like working under both managers, Gundogan told Suddeutsche Zeitung: "There are the two coaches who stand for the two different styles that are currently on the market.
"They live full intensity, are incredibly demanding; you can not switch off for a second in training. Otherwise, there's a b******ing.
"You may be a little bit more scared of Klopp because he's so big and loud and shows so many teeth."
Liverpool moved eight points clear of the reigning champions this weekend after City suffered a shock 2-0 defeat to Wolverhampton Wanderers.
The two sides, who played in the Community Shield in August, meet again in the Premier League at Anfield on November 10.
