"We are all looking for answers now," said Ronaldo on Sky Italia. "We want to understand what is behind this injury, as there are answers to our questions about our work and how we continue. We are always looking for the best possible option."

He added: "I was unlucky in Lisbon because I went to warm up and after 10 minutes the fitness Coach told me I was about to come on.

"So I started rushing through my routine and I got a little pull in my left calf muscle. I decided not to risk it, as to go on could've meant a very serious injury."