Derby went into today's game coming off a great run of four wins in five games, and having taken top spot with a 1-0 win over Blackpool in midweek, spirits were high at the iPro Stadium ahead of the visit of Wigan Athletic.
The Latics have endured a tough start to the season, and arrived at Derby with no win in eight games as Uwe Rosler's side struggled to find the back of the net.
All the signs pointed to a home win today, but Wigan had a glorious chance to take the lead in the first half after Craig Bryson's handball handed James Tavernier the chance to score from the penalty spot, but recent loan signing Jack Butland kept it out - and the Rams took advantage of the miss instantly.
John Eustace put Derby ahead in first half injury time, and with a 1-0 half time lead, Steve McClaren must have felt quite confident that his side would go on to claim all three points.
But they wouldn't have predicted a one-man fightback from former Sunderland winger James McClean. The Irishman drew Wigan level with around 20 minutes to play, and just eight minutes later he handed Wigan the win in a shock turnaround.
Derby remain top of the table after Watford's draw at Middlesbrough, whilst Wigan move up one place into 19th.