Junior Stanislas was the hero as West Ham United won through to the Carling Cup third round with a dramatic 3-1 extra-time win over Millwall at the Boleyn Ground.
The 19-year-old netted twice as the Hammers booked their place in the hat with their first home win over the south Londoners since February 1991.
Neil Harris, the Lions' all-time leading scorer, looked to have won the tie when he latched on to Scott Barron's long throw and drove a low shot past Robert Green on 26 minutes.
Gianfranco Zola's side refused to give up their search for an equaliser, hitting the post through a Jack Collison shot before Junior Stanislas lifted the roof off with an 87th-minute leveller.
Then, when Lions captain Peter Frampton handled substitute Zavon Hines' cross seven minutes into extra-time, the England Under-21 forward showed a steely nerve to send David Forde the wrong way from the penalty spot.
Hines then made the game safe for the 1966 and 1981 runners-up, streaking past Frampton before belting the ball past Forde on 102 minutes.
Tuesday's match - the first meeting between the local rivals since April 2005 - was, to nobody's surprise, keenly-fought affair, with clear-cut chances at a premium at both ends in the early going.
Radoslav Kovac - making his first start since making his move from Spartak Moscow permanent - rattled an early volley over Forde's crossbar as West Ham started the better of the two sides, but it was Millwall who struck first through Harris.
Former Hammer Gary Alexander had already headed narrowly wide when the 32-year-old struck, allowing Barron's throw to bounce before lashing an unstoppable shot past Green from no more than seven yards.
Aside from bookings for Danny Gabbidon, making his first Boleyn Ground start since the Carling Cup quarter-final defeat by Everton in December 2007, and Millwall's Frampton and Marc Laird, the first half passed off without any further major incidents.
Zola, who also handed a full debut to Josh Payne and a start to James Tomkins, sent on a second striker at half-time in the shape of 20-year-old Hines.
The arrival of Hines, who scored on his Hammers debut against Macclesfield Town at the same stage of last season's competition, sparked an immediate increase in tempo and attacking intent from the home side.
Just four minutes after coming on, the Jamaican exchanged passes with Stanislas before finding a third Academy graduate in Collison. The Wales midfielder beat his marker before crashing a left-foot shot against the inside of Forde's right-hand post.
Frank Nouble joined Hines and Carlton Cole in attack with a shade under half-an-hour remaining as Zola went for broke, but it was Millwall who would have the game's next opportunity, Laird firing a rising 30-yarder into Green's side-netting.
With the Hammers committing more and more men forward, the game became increasingly open, with only a superb block from Frampton preventing Nouble from working former West Ham goalkeeper Forde.
As the game entered the final ten minutes, Chris Hackett tested Green with a rising shot from just outside the penalty area.
Then, with just three minutes of the 90 remaining, Julien Faubert found the unmarked Stanislas with an inch-perfect far-post cross that the England Under-21 forward gleefully converted.
Five minutes into extra time and Hines came within a whisker of putting the hosts ahead, only for his shot to roll agonisingly wide following fine build-up play involving Collison and Cole.
West Ham's persistence then paid off in the shape of two goals in the space of five minutes through Academy graduates Stanislas - from the penalty spot - and Hines, finally ending the challenge of Kenny Jackett's side.
There was still time for Forde to deny Faubert a first Hammers goal as the hosts looked to end in style, but a 3-1 victory will send Zola and his players to Blackburn Rovers in confident mood this coming Saturday.