Swindon skipper Andy Gurney brought table-topping Wigan's five-month unbeaten run to a shuddering halt with a sensational first-half strike.
Defender Gurney plundered his seventh goal of the season with a majestic 35th minute volley as resurgent Swindon kept their faint play-off hopes alive with a third win in four games.
Aussie Danny Invincibile put Andy King's men ahead on 24 minutes when he thundered in his sixth goal of the campaign.
Midfielder Invincibile hooked the ball past fellow Aussie John Filan from 16 yards after the influential Gurney had played him through.
Gurney doubled Wigan's woes just 11 minutes later when he thumped in Swindon's second after 18-goal top scorer Sam Parkin had nodded the ball into his path.
Wigan winger Scott McCulloch grabbed a 55th minute consolation goal with a close-range header, but it was not enough to save the Lancashire leaders from slipping to their first defeat since late August.
Wigan manager Paul Jewell refused to condemn his players saying: "We can't be expected to win every game.
"No doubt this will go down as a crisis, but that is not the case, our unbeaten run had to go sometime.
"We've had a good innings so I can't be too hard on my players and hopefully we can go on another run now." Swindon manager Andy King shunned all talk of a surprise promotion push and instead paid tribute to his courageous players.
King said: "We showed great determination, spirit and desire and I was delighted with the way we played.
"We were tremendous in the first half but I expected Wigan to come at us with all guns blazing in the second half so I was delighted we managed to hold on.
"Danny Invincibile in particular was outstanding, but all of my players deserved pat on the back. Wigan are a very attacking side but we marshalled them well."