Chelsea, with Graham Potter on the coaching bench, continues to have a really tough time in the Premier League.
Against Manchester City, they had to replace both Raheem Sterling and Christian Pulisic even before 22 minutes had been played.
Both were injured and replaced by Pierre-Emerick Aubameyang and the talent Carney Chukwuemeka respectively.
19-year-old Chukwuemeka came really close to putting his team in the lead, but at the break it was goalless.
Mancheseter City's Norwegian superstar was also close to scoring, but instead it was a diving duo that scored the lead goal.
In the 60th minute Jack Grealish and Riyad Mahrez entered a double substitution and three minutes later it was Grealish who found Mahrez to make it 1-0 after a neat strike.
With the victory, City are five points behind league leaders Arsenal.
Chelsea are tenth on a modest 25 points.
MORE PREMIER LEAGUE: See Haaland's new goal success in the Premier League (December 28)
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See Haaland's new goal success in the Premier League