Rafael is confident Manchester United can inflict Chelsea's first defeat of the season when the two clubs meet at Old Trafford on Sunday.
Jose Mourinho's men have made a blistering start to the 2014-15 campaign, winning seven and drawing one of their opening eight matches in the top flight to open up a five-point lead over defending champions Manchester City.
United, by contrast, have struggled for consistency, with 12 points to their name as Louis van Gaal attempts to get the most out of his expensive squad.
