United went top of the Premier League, at least temporarily with the win and will head into the global break with plenty of confidence for yet again, the Red Devils won by a resounding margin without ever moving into top gear.
Manchester United vs Crystal Palace is the seventh match of this competition.
Rashford was involved in the goal and looked initially as if he might try to claim it as his free-kick, whipped in from the left, flew in at the far post.
Fellaini has often been a target for criticism at Manchester United, but the Belgian's effectiveness has made him a favourite of the pragmatic Mourinho. United come into this having scored 17 goals in the Premier League so far, as well as a further seven in their two Champions League fixtures.
"I didn't see that [PlayStation football] as much, just a little bit of relaxation, a reaction by the home team with the normal pride to try to score, to try to have a different result and we just relaxed a little bit".
86-goal attacker could join Premier League strugglers Crystal Palace
Crystal Palace is making history in the English Premier League.
However, their most recent victory over Manchester United came in the League Cup in November 2011 - Darren Ambrose and Glenn Murray scoring in a 2-1 win in the quarter-final. Mata scores - Rashford leaves the Palace defence stranded as he scoots away from Ward, driving to the byline. In his five years in the Premier League before this season, Benteke had scored on 30 of 72 non-penalty clear chances.
United's fast start didn't last, and the hosts took their foot off the gas after taking the lead.
Another eye-catching display from United's teenage England star, in which he produced two fine assists.
Indeed, the Portuguese manager will be without as many as seven first-team players ahead of the visit of Roy Hodgson's men on Saturday. Conor Wickham and Wilfried Zaha will also miss out for Hodgson's side due to respective injuries.