Mancini said: "Sometimes you don't win. We know that it's impossible to stay top for all 38 games.
"Every team has a plan but if we don't score in the first half it's difficult.
"We will probably have another eight or nine games in next 20 days like this.
"West Bromwich played with all their players around the ball and you have to find a solution if you don't score quickly in the first half."