Derby and Nottingham Forest share the biggest rivalry in the Midlands, according to Rams goalkeeper Adam Legzdins.
Hailing from near Stafford in the west Midlands, Legzdins was brought up on the Birmingham derby and the Black Country rivalry between West Brom and Wolves.
The 26-year-old admits he never realised the ferocity of the feeling between the two sets of supporters on the other side of the Midlands until he signed for Derby.
Legzdins, who began his career as a trainee at Birmingham, joined the Rams from Burton in the summer of 2011. He made his debut for the club against Forest at the City Ground as a second-minute substitute after Frank Fielding was sent off.
Recalling that game, which Derby came from behind to win 2-1, Legzdins said: "It was not the best way to make my debut - not only for Derby but in the Championship - but I have fond memories looking back.
"I remember the atmosphere was buzzing, I didn't realise how big a game it was. Not coming from the area, I suppose I didn't realise how big the derby game against Forest was.
"My local derbies are West Brom-Wolves and Birmingham-Aston Villa so I wasn't aware of how big Derby-Forest is.
"But living in the area now and being at the club for 18 months, I've got a feel about what it means to the sets of fans.
"Everyone knows they are two big clubs steeped in history but it's also a massive rivalry - compared to the other one's I mentioned it's probably actually bigger."