Sky Sports football expert Niall Quinn believes Manchester City's defeat to Juventus was a real lesson learnt.

The Turin club beat City 2-1 in the Champions League opener on Tuesday night despite taking the lead in the 57th minute.

City were favourites to win the game but they failed to bring their strong Premier League form to the continental tournament which Quinn feels will be important education for Manuel Pellegrini's men.

"We got an abject lesson in City's shortcomings and frailties," said Quinn.

"Juventus have given an exhibition of European professionalism, Champions League professionalism, and Manchester City's great start to the season is in tatters.

"You lose your first game at home and you have all the questions again… the good start to the season seems a distant memory. Tonight is tough for Man City to get over."