A goal in the 89th minute resulting from Frank Lampard's downward header produced a dizzying climax to a game of remorseless but unrewarded pressure from West Ham.
Minutes earlier Ian Wright, a constant threat to Northampton, saw his strike cruelly ruled offside, but Ian Atkins' bold team certainly earned their progress to the next round.
West Ham were missing the likes of Eyal Berkovic, Neil Ruddock, John Moncur and John Hartson. However, their manager, Harry Redknapp, was able to recall Dicks, the club's footballing soul, after 18 months out of the game with a debilitating knee injury.
Dicks' influence was immediate and his overall performance was acclaimed as "absolutely magnificent" by Redknapp. Dicks provided the launching point for a relentless succession of attacks but Northampton stood firm. A defence often comprised of five men proved an impenetrable bulwark. The centre-back pairing of Ian Sampson and Colin Hill was busy and efficient, while in goal Woodman was outstanding.
Northampton cleared a succession of corners, Dicks heading narrowly over and Woodman acrobatically saving from Ian Pearce's goal-bound effort.
A minute before half-time Steve Potts for once breached the Northampton defence, but tumbled over with only Woodman to beat. West Ham's appeals for a penalty were waved brusquely away by the referee, Dermot Gallagher, .
Having been untroubled for the entire first half, Shaka Hislop, the Hammers goalkeeper, was abruptly stirred into action as Andy Impey's error freed Colin Freestone, the scorer of both Northampton's goals in the 2- 0 first-leg win. Put one on one, he stormed forward and a goal then would have left West Ham needing to score four. Hislop's nerve held and he forced Freestone wide, allowing Impey to recover and block the striker's crisp shot.
It was a fleeting moment of relief and back at the other end Wright forced an instinctive save from Woodman. The effervescent Wright was denied again three minutes later, Hill clearing another effort from the goal-line.
West Ham United (4-4-2): Hislop; Impey, Pearce, Ferdinand, Dicks; Sinclair, Lampard, Potts, Keller; Abou (Omoyinmi, 71), Wright. Substitutes not used: Forrest (gk), Breacker, Hodges, Partridge.
Northampton Town (4-4-2): Woodman; Sampson, Hill, Warburton, Frain; Gibb, Peer, Hunter (Spedding, 65), Parrish; Wilkinson, Freestone (Corazzin, 79). Substitutes not used: Turley, Heggs, Dobson.
Referee: D Gallagher (Banbury).Reuse content