Real Madrid star Cristiano Ronaldo says they won't underestimate Champions League opponents Manchester City.

The second-leg will be staged in Madrid with the score locked at 0-0.

Speaking about his Real Madrid's upcoming game against Manchester City, which the Portuguese is hoping to play in despite a recent injury, Ronaldo made it clear that his side are aware of the danger posed by City.

"We know we're facing a difficult challenge," he said.

"Manchester City are in the semi-finals for a reason, it isn't easy beating Paris Saint-Germain; City are a team with very few weaknesses," the striker stated.