Matty Pearson's strike deep in to extra-time gave Accrington Stanley victory over the Clarets in the first ever competitive meeting between the clubs.
The full back drilled a low effort beyond debutant goalkeeper Nick Pope following a scramble in the box in the 119th minute to dump the Clarets out of the EFL Cup and secure a third round tie against West Ham at the Olympic Stadium.
Boss Sean Dyche made 10 changes for the competition, with just Sam Vokes remaining from the weekend win over Liverpool, but the transformation merely served to highlight the lack of depth at the club.
Aside from James Tarkowski and Aiden O'Neill, who was arguably the stand out player on his professional bow, there weren't many who made an impression at the Wham Stadium.
Opportunities were few and far between, with the best of those only considered to be half chances.
Elliot Parish plucked Michael Kightly's deflected header out of the air after Lukas Jutkiewicz found space down the right hand side to deliver a cross.
The hosts rarely threatened in the opening half but they went close when Mark Hughes guided the ball wide at the back post after John O'Sullivan's cross was diverted in to his path.
The Clarets had been knocked out of the competition at the first attempt in two successive years, falling to Sheffield Wednesday and Port Vale respectively, and their early profligacy suggested that a third consecutive disappointment was on the cards.
Vokes pulled an attempt wide of the far post after bringing down Kightly's lofted pass well while Johann Berg Gudmundsson failed to capitalise on Kightly's incisive assist as Parish raced off his line to foil the Icelandic international.
The best chance of the half fell to Jutkiewicz who went within a whisker of opening his account for the club. Kightly did well to beat Janoi Donacien at the byline and roll the ball across the face of goal but the former Middlesbrough man couldn't get a stud to it at the back post.
The tempo or exhilaration didn't really lift after the break as both sides failed to find a way through.
Vokes's ferocious drive dipped just over the bar after taking a nick on the way through while Jutkiewicz flicked a header wide of the upright after throwing himself at his strike partner's pass.
Pope denied Sean McConville with a routine save soon after and Parish did the same at the other end to prevent Gudmundsson from breaking the deadlock.
Substitute Paddy Lacey side-footed an effort wide when picked out by Rommy Bocco and Andre Gray steered wide from Gudmundsson's centre.
The Clarets striker had a superb opportunity to decide the tie late on, when unselfishly assisted by Gudmundsson, but Parish stayed big to thwart him from close range and the game went in to extra-time.
Arron Davies almost provided the breakthrough early on in the additional period but his deflected shot dropped the wrong side of the upright with Pope rooted to the spot.
Parish got a fingertip to Scott Arfield's drive as play progressed to touch the ball to safety before Bocco could and should have found the net.
Donacien's cross dropped beyond Kevin long and Pope but the goalkeeper did well to get back in to position to save well from Bocco's free header.
However, after O'Neill's attempt whistled past the post, Stanley won the match with just 60 seconds remaining.
The Clarets failed to clear a ball played in to the box from the left hand side and Pearson lashed the loose ball in to the corner.