Perhaps Portsmouth's 5-0 victory over Millwall on Saturday that brought them up to seven games undefeated lulled them into a false sense of security.
Especially as Wimbledon were without 16-goal David Connolly and influential Jobi McAnuff, who started on the bench after injury.
Both halves suffered long periods of stalemate and as always if the Dons aren't nailed early on they push on and frustrate opponents.
Bringing on secret weapon Patrick Agyemang for Wayne Gray in the 57th minute, he produced his usual tricks and things began to happen for the Londoners.
Wimbledon's attack was aided and abetted by midfielder Nigel Reo-Coker, as the Dons stopped Pompey from gaining their 10th away victory.
Pompey had to wait until the 26th minute for the first shot on target which eventually led to their goal.
Paul Merson's pass stranded two defenders for Svetoslav Todorov, from five yards out his effort was brilliantly saved by the diving Kelvin Davis.
The loose ball fell back to Todorov who turned and laid it back for Merson. The former Arsenal favourite drove the ball home from the edge of the box.
In the second half Wimbledon won the territorial battle, but couldn't pull Pompey about enough to create any holes, that was until the equaliser in the 65th minute.
Peter Hawkins moved up from defence on the left flank. His cross found Neil Shipperley and the captain nodded the ball down for Agyemang to gleefully scoop the ball beyond the goalkeeper.
The Pompey fans in the 10,000 plus crowd lost their voice and with four minutes left frustration turned to despair.
Reo-Coker fought his way down the left and battled into the Portsmouth box. His pass reached man of the match Gareth Ainsworth, who smacked the ball past Shaka Hislop for the unexpected winner.