Victor Obinna returned from suspension in style, netting a hat-trick to fire West Ham United through to the FA Cup Sponsoredby EON fifth round at the expense of Nottingham Forest.
The Nigeria international had missed the previous three matches after being sent-off in the Carling Cup semi-final first leg win over Birmingham City on 11 January.
Obinna took his frustration out on Championship promotion-chasers Forest, who arrived at the Boleyn Ground having not been defeated in eight matches dating back to 29 November 2010.
Indeed, Billy Davies' side showed why they had won six of their previous seven matches during a thoroughly entertaining 90 minutes, but West Ham's quality - and in particular that of the Hammers' No33 - that ultimately shone through.
West Ham made a bright start and took a little more than three minutes to take the lead.
Lars Jacobsen took a short corner to Mark Noble, whose shot was flying wide of the far post before Obinna stuck out his right foot to divert the ball past Forest goalkeeper Lee Camp.
Unfortunately, rather than settle the home side, the goal appeared to spur the visitors into action and, after creating a host of chances, Forest levelled through veteran target man Dele Adebola. The burly striker took a pass from David McGoldrick before poking a shot inside Robert Green's far post.
Having equalised, Forest went on the offensive, with Radoslaw Majewski, former Hammer Chris Cohen and Lewis McGugan all going close to putting their side in front before McGoldrick did just that five minutes before half-time.
Cohen's right-wing free-kick was inadvertently flicked on by Herita Ilunga and Green could only claw the ball high into the air. When it came down under the crossbar, the former Southampton forward reacted quickest to head the ball in from close-range.
Two minutes later, West Ham were level again in truly miraculous fashion. Obinna streaked down the right wing before aiming a cross-shot towards the six-yard box. Instead, the ball flew high over the head of Camp and into the far top corner for a spectacular equaliser.
The second half was a much easier watch for the home fans inside the 29,287-strong crowd - including 5,800 travelling Forest supporters - as the Hammers started to dictate play and create chances at will.
Just seven minutes into the second period and West Ham were ahead courtesy of that man Obinna.
When Freddie Sears lifted the ball into the penalty area following a Jacobsen corner, Joel Lynch hauled back Winston Reid and referee Michael Oliver immediately pointed to the spot.
After a quick chat with regular penalty-taker Noble, the on-loan Internazionale man sent Camp the wrong way from 12 yards.
Having gone ahead, West Ham began to dominate and Frederic Piquionne was denied a goal by the former England Under-21 goalkeeper, who had earlier also kept out a low shot fromNoble.
Camp was called into action again on 62 minutes, denying Pablo Barrera a first West Ham goal with an acrobatic save.
Davies sent on Wales striker Robert Earnshaw and Nathan Tyson in an attempt to stem the Hammers tide, but it was still the home side who carried the greater threat as the game entered its closing stages.
Piquionne and Sears both went close as West Ham threatened to make the tie safe but, with a one-goal advantage, the home fans were forced to chew their fingernails until the very end.
Wes Morgan powered a header wide before Chris Gunter forced Green into a low save as Forest made one final push, but Avram Grant's side held on to win through to the last-16 for the second time in three seasons.