Reading had won nine of their previous 11 games against Derby but came into the match with seven first-teamers missing, which meant a first league start for 19-year-old Jordan Obita.
The Royals had not conceded in 285 minutes of Championship football but their defence was almost breached in the eighth minute when Johnny Russell got in on the left and Alex McCarthy could only push out his low shot but Craig Bryson could not turn in the rebound.
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Police body cam footage captured the incident in Brighton in June 2013.