It meant asking winger Shaun Wright-Phillips to play at right-back and Glen Johnson to play as a central defender after Ricardo Carvalho was forced out of the game with a knee injury in the opening half.
But the changes worked like magic and Mourinho emerged with another glowing testimony to his managerial reputation even though he knew he was taking another massive risk.
One more injury in the second half would have brought fierce criticism of his tactics but, unlike an FA Cup tie at Newcastle three seasons ago, his luck held this time.
Mourinho declared: "I think the players were brave and fought a lot. They were brave to accept some of the difficult situations. It was not easy for Shaun Wright-Phillips to play right-back or for Glen Johnson to play as a central defender.
"It was not easy for Tal Ben Haim after just two months at the club to find himself leading the defence.
"But I asked them at half-time if somebody was feeling a bit weak or feeling a bit of an injury. I wanted to make two changes and I wanted to finish with 11 men.
"They told me everybody was fit and ready to go so I made the changes. When we were leading 2-1 there were no more changes I could make. I could have made if more defensive but I thought our positive attacking would help us score more goals.
"It is difficult to come to this stadium and win so I am very please with the result and the players.
"Making the changes was a big gamble but if one day it doesn't work - like at Newcastle in my first season - I am criticised. But I sleep good because I tried.
"The worst thing in life is when you don't try. That is the message I give to my kids all the time. I have to try in my job."