Wayne Rooney opened the scoring after just 15 minutes, and while Frazier Campbell later leveled, a Patrice Evra header gave United another lead just a minute before the break.
Rooney should most likely have seen red early on for a kick to the calf of Jordan Mutch, but he got away with yellow from referee Neil Swarbrick.
The Manchester United striker used an outstanding spin move to score seven minutes later after receiving a beautiful flick-on from Javier Hernandez in the box.
It took a lot of hard work from Cardiff City, but they slotted through two excellent through balls from Peter Whittingham and Mutch to find Frazier Campbell open past his man for a goal of their own.
The scoreline again wouldn’t last long though, as Patrice Evra took a corner from Wayne Rooney and headed it far post past David Marshall for a 2-1 lead.
If Manchester United can hold on for all 3 points, they would move past Manchester City into fourth place in the Premier League table.