Ronaldo struck after halftime thanks to a howler from Spurs goalkeeper Heurelho Gomes
"It was a good win tonight and this means we have taken a very important step forward," the Portuguese international said.
"Our ambition at the start of the campaign was obviously to go very far in this tournament. We are close to the final now but we are facing a very difficult rival next [in Barcelona]."
Asked about Real Madrid's opponents in the next round, Ronaldo reminded everyone that the current La Liga champions are a team like any other, with weaknesses of their own.
"They are a great team but they are not from another planet; they are human just like us," he continued.
"They play good football, sure, but so do we. We are feeling good both physically and mentally. I hope that we are going to come out on top in these encounters against them."