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.
More top news
Rain clearing east tonight for a dry but fresher day tomorrow with plenty of sunny spells.
Heavy rain clearing east for a dry but fresher day tomorrow with some hazy sunshine.
Rain becoming heavy at times this afternoon before clearing tonight. Dry with hazy sunshine tomorrow but feeling fresher.