AFC Wimbledon produced a stunning performance to hold off a second-half comeback from West Ham and earn a 4-2 FA Cup scalp
The side bottom of League 1 turned the form book on its head and showed more industry and desire than their Premier League visitors in the first half, and were rewarded with a comfortable lead at the break through Kwesi Appiah's deflected opener (34) and Scott Wagstaff's smart finish on the break (41)
West Ham looked far more competitive following a triple half-time substitution from Manuel Pellegrini, but not before Wagstaff had scored Wimbledon's third just 37 seconds after the restart when his superb flick from Appiah's cross beat Adrian
The Hammers threatened to extinguish hopes of an upset through two of those substitutes, with Lucas Perez firing in from a corner (57) and Felipe Anderson scoring direct from a free-kick (71)
But Wimbledon did not let their increasing pressure tell and wrapped up a famous victory when 19-year-old Toby Sibbick nodded in Anthony Wordsworth's cross with two minutes remaining, sending the sell-out home crowd into pandemonium
Pellegrini made six changes from last week's defeat at Bournemouth but the Hammers' side still had Premier League experience from back to front, although in the opening 45 minutes it was difficult to believe they were the top-flight side in the tie
Wimbledon worked the ball forward with quality and pace and although West Ham hit the post through a deflected Javier Hernandez effort, it was one of few half-chances they fashioned before the break
Instead, Wimbledon took the lead with a slice of good fortune their play had thoroughly deserved when Appiah's shot from 20 yards took a big deflection off Angelo Ogbonna to wrong-foot Adrian
Their second, seven minutes later, summed up their performance when Appiah robbed Pedro Obiang in midfield, with Wagstaff picking up the loose ball and he raced beyond the West Ham defence to slot inside the near post
Pellegrini threw on Anderson, Perez and Ryan Fredericks at the break but their first job was to watch Wagstaff volley in Appiah's measured cross from the left with a brilliant flick into the far corner
From then on, the visitors had the lion's share of possession and play but with a three-goal handicap, had it all to do
 But they certainly smelt an opportunity once Perez fired home powerfully once Michail Antonio's shot had been saved by Aaron Ramsdale
The Hammers kept on knocking and Anderson curled in a second from a 25-yard free-kick following a clumsy challenge from Will Nightingale, but Wimbledon held firm and denied them any further clear-cut chances
They gave them a lesson in creativity when the hosts resisted the temptation to pull men back once a late corner had been cleared, allowing Wordsworth to pick out substitute Sibbick, who nodded in his first goal in more than a year from close-range, sparking scenes of wild celebration in the stands well before the full-time whistle with a spot in the fifth round assured
Going on this performance the buy of little-known Connolly from Irish side Dundalk looks a stroke of genius
 On his first start since his January 3 arrival, he made three key passes, as many as anyone else on his side, and his crossing deserved more from his forward team-mates
He won 78
6 per cent of his 14 duels on the night - a higher proportion than any other Wimbledon player - and gave Arthur Masuaku a torrid time on the right until he was withdrawn exhausted with four minutes left
Wimbledon face another tough test when they travel to promotion-chasing Sunderland in League 1 next Saturday at 3pm
 West Ham are back in action on Tuesday night, when they visit Molineux to face Wolves at 7
45pm
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