Pellegrini said: "I'm going away happy because we won and scored three goals, but I'm not happy with the game we played. We need to go out onto the pitch with more intensity.
"It was a difficult game after our elimination from the Champions League.
"We did not have a good first half, we did not have the creativity to not break through Sporting's defence.
"But what's important is that after the goal we conceded we knew how to react and we improved a lot in the second half.
"The team won and that's the most important thing. I think it's impossible to win every game playing well. As well as that, we not only won but we did it by scoring three goals.
"We knew it was going to be a tough game, they (Sporting) have a great counter-attack and they are doing well away from home."