Ronaldo has netted 15 times in the Champions League this term, while no player has scored more times in the history of the European competition than the Portuguese.
The 33-year-old will enter the match off the back of scoring 44 times in 43 matches in all competitions this season, but Lovren is confident of dealing with the attacker in Kiev on Saturday night.
"Throughout 15 years, every year [Ronaldo] scores more than 30 goals. Even if he has a bad season he scores 30 goals, so you need to pay attention to that," Lovren told reporters.
"We play in the Premier League against some of the best strikers in the world and we know how to defend like a team. Of course some parts of the game it will be one-against-one. It will be tough but it's a challenge that I'm ready for."
Madrid are bidding to win the Champions League for the third year in succession.