Anthony Elding got the game's only goal to see Rochdale of League One through to round two of the Carling Cup at the expense of Championship side Barnsley.
The striker, a free summer signing from Kettering, headed in the winner against the run of play from Joe Thompson's cross early in the second half.
Barnsley had plenty of chances either side of that, Jacob Butterfield firing wide when well placed three times.
Liam Dickinson also missed from close range as Dale held on for a shock win.
It makes it two defeats from two for Mark Robins' side this season, after Barnsley's 4-0 defeat at QPR in their opening league game on Saturday.
And they only had themselves - and their poor finishing - to blame, not least Butterfield who fired an early chance over, curled another effort wide of the post, saw another shot held by Rochdale goalkeeper Josh Lillis and was inches off target with a header.
Lills also denied Adam Hammill from range, before Tykes debutant contrived to miss from close range after good work by Jay McEverley late in the piece.
It all meant Dale need only convert one of their chances - and Elding obliged with his first goal for the club.
Live text and stats
Tuesday, 10 August 2010
06 Foster (Hassell 80)
19 Butterfield (Devaney 54)
05 Doyle yellow card
10 Lovre (Hume 53)
15 Thompson yellow card (Done 79)
14 Akpa Akpro (Elding 46 yellow card)
Ref: Geoff EltringhamAtt: 4,107
Attempts on target
Attempts off target
95:45 The game gets underway.
90:00+4:03 The assistant referee signals for offside against Liam Dickinson. Josh Lillis takes the free kick.
90:00+2:47 Defending throw-in by Jay McEveley (Barnsley).
90:00+2:15 A cross is delivered by Matt Done, Anthony Elding has an effort at goal from the edge of the area that misses to the right
of the target.
90:00+1:32 Goal kick taken long by Josh Lillis (Rochdale).
90:00+0:50 Defending throw-in by Joe Widdowson (Rochdale).
89:35 Adam Hammill gives away a free kick for an unfair challenge on Jason Kennedy. Josh Lillis restarts play with the free kick.
88:41 Inswinging corner taken by Jay McEveley.
88:12 Attacking throw-in by Bobby Hassell (Barnsley).
87:48 Defending throw-in by Kieran Trippier (Barnsley).
85:44 The offside flag is raised against Iain Hume. Josh Lillis restarts play with the free kick.
84:54 Goal kick taken long by Josh Lillis (Rochdale).
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.