The Dutchman has netted an impressive 23 goals for United in all competitions so far this season, his latest strike coming in the 2-0 win over Everton on Sunday.
And Real Madrid defender Ramos insists he needs no reminding of the 29-year-old’s threat ahead of the first leg of the last-16 tie at the Bernabéu on Wednesday.
“Van Persie is on very, very good form,” Ramos said. “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.”