Eto'o, despite having scored the most league goals of any of Chelsea's three senior strikers, did not make the bench on Saturday.
Explaining why he opted to go with Fernando Torres, Mourinho said: "There's nothing wrong with Samuel. I just felt in this kind of match - away from home, against normally defensive teams, aggressive defenders - I thought to go with Fernando (Torres) and, if I need to risk in the last part of the game I'd use Demba (Ba).
"You see, Eto'o scores goals but at home. He scores in the league, in the Champions League but all of them at home.
"Playing away is more difficult for him. I think he is our best striker to play at home because of his technique, his movement and his understanding with Eden (Hazard) and Oscar.
"For me, he is best to play at home. Away he is showing some difficulties."
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