Reading manager Brian McDermott was left frustrated after the 3-1 loss at Cardiff.
The Bluebirds stormed into a three-goal lead inside 36 minutes courtesy of Joe Mason, Aron Gunnarsson and Kenny Miller.
Former Cardiff midfielder Jobi McAnuff pulled a goal back for the Royals on the stroke of half-time, but it proved immaterial as the home side cruised through the second period to move into third spot.
The loss ended a run of four successive victories for Reading, much to McDermott's dismay.
He said: "We didn't perform and that is the disappointing thing for me.
"
Give credit to Cardiff, who have beaten us twice this season.
We have to move on quickly."