There was a completely different back four on the pitch for City but it did not stop them keeping a clean sheet as they beat West Bromwich Albion 1-0 at Etihad Stadium thanks to Edin Dzeko's first-half goal.
The Bosnian, who netted a double against the Baggies earlier in the season, received a chipped cross from Carlos Tevez which he beautifully volleyed home in the 35th minute which was enough to take all three points, delighting Mancini.
"I thought that it was a difficult game. We changed a lot of players, we took some risks, but in the end it was important to win this game," he told Sky Sports.
"After 10 minutes, we started to play very well. We had five incredible chances to score, but we were missing. For that reason, we suffered more in the second half.
"They are a good team. They have had a fantastic season, they play good football. We knew that it would be a difficult game."