Goalkeeper Matt Baker pulled off his second penalty save in four days as MK Dons continued their resurgence and dented Bournemouth's play-off hopes.
Baker saved from the spot in Friday's 1-1 draw at home to Swindon.
The Dons keeper repeated those heroics by keeping out Garreth O'Connor's first-half penalty as Danny Wilson's side extended their unbeaten run to nine matches.
The battling Dons had the better of a drab first half and could have been in front inside the opening 13 minutes.
Pacy midfielder Wade Small should have done better when Leon Crooks crossed from the left but shot just wide from the edge of the area.
Eddie Howe had Bournemouth's first attempt on goal when his header was deflected wide by veteran Dons defender Steve Palmer in the 15th minute.
Goalkeeper Neil Moss was called into the action for the first time five minutes later when he turned away Dean Lewington's long-range effort.
John Spicer headed a Wade Elliott centre wide in the 25th minute before Trent McClenahan hit the referee with a long-range shot and the ball deflected wide.
On-loan Fulham defender Adam Green put a 25-yard free-kick over the crossbar in the 30th minute as the game continued to flow from end to end.
Bournemouth were gifted a chance to take the lead five minutes later when leading score James Hayter was tripped by Dons defender Crooks.
O'Connor stepped up to take the resulting penalty but man-of-the-match Baker guessed the right way and, diving full length to his right, pushed the ball behind to safety.
Bournemouth came out fighting after half time and Baker pulled off another fine save to keep out O'Connor's volley six minutes after the re-start.
The home side fell behind 18 minutes from time when Australian defender Gareth Edds smashed in his second goal of the season.
Big striker Clive Platt headed Izale McLeod's cross into Edds' path and the full-back picked out the top left-hand corner of the net to earn the Dons an unexpected victory.