Karanka was again filling in for coach Jose Mourinho after the 3-1 triumph.
"The teams work and attitude throughout the season is what matters. We have a fantastic group of players that makes all of us very happy. They deserve to be champions and we must keep up the good work till the end," he said.
"People say Mourinho has a defensive style, but 107 goals isn't all that bad.
"Sporting defended well and we knew they would. A draw wouldn't do much for them and it's a shame they're in that situation because of the attitude the showcased. They caused problems for us and made it difficult to win."