The Scotland international said: "You could see by my reaction that it was not the case, but I felt something on the side of my head more than him just leaning in towards me.
"As usual at a corner there was some pushing and shoving but Ronaldo went into me first and then seemed to swing his leg. I thought that if he was going to try to shove me to get a run on me I would just get tighter and we went head to head as footballers often do for some reason.
"I definitely felt something more than just him leaning his head on mine, though. Whether he meant it I'm not sure but the referee was right there and saw fit to show him a red card."