Adam Virgo's late penalty for Bristol Rovers condemned AFC Wimbledon to defeat on their Football League debut.
Scott McGleish fired Rovers ahead with a low angled drive, before Matt Harrold nodded in from six yards to give new boss Paul Buckle a dream start.
Jamie Stuart pulled one back when he headed in Sam Hatton's free kick.
Substitute Charles Ademeno equalised with a smart turn and shot in the box but Virgo converted from the spot to win it after Brett Johnson handled.
The two sides were separated by two divisions last season, with Rovers subsequently relegated from League One.
AFC Wimbledon completed their meteoric rise through the non-league since being formed in 2002 - when Wimbledon FC were relocated to Milton Keynes - by beating Luton Town on penalties in the Blue Square Bet Premier play-off final.
There was a carnival atmosphere at Kingsmeadow before kick-off, but that was soon deflated by two goals in three minutes from the visitors.
McGleish, one of 10 debutants in the Rovers starting line-up, grabbed the first, drilling the ball low past Seb Brown after Matt Gill had dispossessed Ricky Wellard as he tried to bring the Dons keeper's throw under control.
The veteran striker then seized on the rebound after Brown had saved another shot to turn provider by crossing for Harrold to head in.
Rovers keeper Scott Bevan smothered at Luke Moore's feet to keep his side's two-goal lead intact, but was then left helpless as Stuart powerfully flicked home Hatton's precise delivery to go down in history as the scorer of AFC Wimbledon's first Football League goal.
Harrold was denied a second on the stroke of half-time by a combination of Gareth Gwillim's brave block and crossbar, while after the break Brown had to be alert to keep out Gill's snap-shot.
The Dons came increasingly into the game and grabbed a deserved equaliser when Ademeno pounced on Lee Minshull's knock down to turn and shoot past Bevan from eight yards three minutes after coming on.
But after Brown had pulled off a string of saves to keep his side on terms, there was a sting in the tail as Johnson flung an arm at a hanging cross and Virgo coolly sent the Dons keeper the wrong way from the spot.
VIEW FROM THE DRESSING ROOM
AFC Wimbledon manager Terry Brown told BBC London 94.9:
"It was a very eventful game and I just have an overiding feeling of disappointment at the way we played today.
"We need to play better than that and we can play better than that and we looked nervous today.
"We never really looked comfortable at the back."
Bristol Rovers manager Paul Buckle told BBC Radio Bristol:
"It was exciting. I tried to say to the players let's get on the front foot, try and get excited and win games and today we've done that.
"I'm positive our attempts on goal outweighed Wimbledon's and this was a tough place to come to today.
"I thought our supporters were first class and didn't disappoint in any shape or form."