Real Madrid defender Sergio Ramos has insisted that the Spanish giants must be aware of Manchester United's in-form striker Robin van Persie.

The Dutchman is likely to start against Los Blancos in the first leg of the Champions League round-of-16 clash at the Bernabeu on Wednesday.

"Van Persie is on very, very good form," The Guardian quotes Ramos as saying. "We hadn't seen him this good for years. He's quick, strikes the ball well, he's a constant nuisance.

"[Wayne] Rooney's different. He's hard-work, heavy going. He enjoys the physical challenge. I prefer that, to be honest. I like that defender versus striker battle, that challenge."

Meanwhile, former United defender Gary Neville believes that the Red Devils will have to double up on Cristiano Ronaldo in order to stop him from controlling the game.