Real Madrid 's ace forward Cristiano Ronaldo  has sent an alarming Champions League warning to former club Manchester United  after his brace sunk rivals Barcelona  in the second leg of Copa Del Ray semifinal at Nou Camp on Tuesday.
Manchester United boss Alex Ferguson and his No 2 Mike Phelan were in the stands, watching their former prodigy single-handedly destroying the Catalan giants, the Sun reports.
Madrid head to Old Trafford next week with their Champions League last-16 second-leg tie poised at 1-1, and the former Red Devils favourite, who was targeted by a home supporter's laser pen, said this win gives them enormous confidence for the game against United.
Ronaldo added it was a great game and they played brilliantly, adding from the first to the last minute they were very serious, with a great attitude.
The Portuguese claimed Madrid played better than Barcelona, adding to score three goals at the Nou Camp is extremely complicated.
Rafael Varane added Madrid's third to clinch a 4-2 aggregate win before Jordi Alba grabbed a late consolation for Barca.
Ronaldo struck the opener from the spot on 13 minutes after Gerard Pique brought him down, and he added a second after 56 minutes to all but kill off the tie as it left Barca needing three to go through.
Varane headed Madrid's third midway through the second half before Alba netted for Barca with a minute left. (ANI )