City's defeat to Nottingham Forest on Saturday afternoon means the side are now six points behind champions Arsenal in the Premier League title race.
Enzo Maresca's side started the campaign with seven consecutive league victories but have now lost their last three for the first time in two years.
City cannot afford many more slip-ups if they want to keep pace with Arsenal, who look ruthless this year after beating Hull City 1-0.
As the club enter the one week international break, Doku has spoken to the club website about how his side need a break to rejuvenate themselves.
"First half we were behind 2-0, playing away to a side like this and losing 2-0 is making things difficult for ourselves. We are used to playing every two days. That’s not a reason. If you ask me for the reason for our first half I don’t know. We go behind very early in the game and that changes a lot," said Doku on the club's official website.
"We reacted too late. If we had started the game like this it would have been different. In the second-half we played without brakes, we were very offensive and tried to create things. We scored early but a team like this are very dangerous on counterattacks.
"We need to be fresh minds, start again and analyse what we can do better and move forward. The international break comes at the right moment for us to analyse and come back refreshed."
City are the first top-flight team in 122 years to win their first seven and lose the next three, a record no title-chasing side will be envious of.
After the break, the club face Fulham at home as they seek to bounce back and close the gap on the Gunners.