The Argentine's goal sent Real to the top of the standings.
"The important thing is that we played well and that we're leaders tonight, but nothing will be over for a long, long time," he said.
"We knew all our games couldn't be easy and knew Real Sociedad would put pressure on us. We were aware of how difficult this venue is; in fact, Barcelona drew here. We simply managed to win and we're happy for it.
"I'm very happy for scoring again. Karim and I try to help the team and we're happy about that."