Atletico Madrid coach Diego Simeone says they'll be wary of Manchester United striker Cristiano Ronaldo tonight.

The first-leg of the Champions League round 16 tie will be held in Madrid.

Simeone said, "Cristiano is a monster.

"He is an extraordinary football player and he has been crucial in all the clubs he has played in.

"It is clear that he has done a lot of damage to us in previous duels where we have met him. He is playing on a strong team again now."