Derby suffered a 1-0 defeat to Forest in the East Midlands derby away from home at City Ground.
Nelson Oliveira’s goal in the fifth minute proved to be the difference between the two sides in the Championship game.
Former Derby defender Johnson was watching the match, and he has admitted on Twitter that Forest were the better team.
Over the course of the 90 minutes at the City Ground, hosts Forest had just 34% of the possession, took 15 shots of which four were on target, and earned two corners.
Dougie Freedman’s side are now 15th in the Championship table with 17 points from 16 matches, seven points above the relegation zone.
The Reds will take on Brentford away from home in the league after the two-week international break.