Darlington gate-crashed Peterborough United's promotion party and will now have to beat Rochdale in a two-legged Play-Off semi-final if they are to progress through to the Final at Wembley Stadium on Bank Holiday Monday.

Posh's biggest league crowd of the season, 10,400, was in attendance to celebrate elevation to the Coca-Cola Football League One, but Quakers dampened the home side's spirits, despite having just two shots all game.

Goals either side of half-time from Jason Kennedy and Micky Cummins earned a makeshift Darlington side victory on a day in which they also re-wrote the record books.

In the closing stages of the game teenage striker Curtis Main wrote his name in the Quakers record books when he became their youngest ever player, at the age of 15 coming on as substitute.

The game was not without incident with goalkeeper David Stockdale joining the ever-increasing number in the treatment room. He limped off with a bruised foot shortly after Kennedy's opener, which came in the third minute, and must now be a doubt for the first leg of the play-offs next Saturday.

The Quakers silenced the home crowd early on when following good play up the right involving Clark Keltie, Neil Wainwright's cross was fired towards goal by Ricky Ravenhill and received a hefty deflection off Kennedy to wrong-foot the Posh keeper.

But just two minutes later Stockdale collapsed in a heap on the edge of his penalty area after a collision with Aaron McLean.

Alan White's backpass left Stockdale and McLean contesting a 50/50 ball with Quakers' keeper coming off second best.

After treatment he continued for seven minutes but was clearly struggling so Polish keeper Przemyslaw Kazimierczak came on for his debut.

He made several good but comfortable saves as Peterborough enjoyed the majority of the possession but Darlington's defence - without the rested Steve Foster - held firm, and limited Posh's opportunities.

Kazimierczak's best first save came when the ball ricocheted towards goal after it hit both Kennedy and Peterborough's Craig Mackail-Smith following a cross by key player George Boyd.

He was a bag of tricks on the left wing and a header of his in first half injury time was only kept out by Kazimierczak who made another save just after the break to catch a Mackail-Smith volley.

It proved decisive because 60 seconds later it became 2-0. Adam Newton was dispossessed and Craig Nelthorpe passed the ball across Posh's penalty area for Cummins to slam home from eight yards.

In the second 83rd minute Darlington created history with manager Dave Penney sending Main coming on and in the limited time he had the teenager showed willingness to get involved.

Despite not being the tallest, he even used his strength to beat experienced former Hartlepool defender Chris Westwood in the air after meeting a left-wing cross, although the chance to nothing.