There have been more entertaining Boxing Days at Upton Park – many of them – but few of such potential significance.
Portsmouth arrived a point behind West Ham and in revitalised mood under Avram Grant, but despite dominating most of the second half, there was nothing for them. Now they have much to do to become only the second Premier League team to avoid relegation after spending Christmas on the bottom of the table.
The home side began nervously, improved in confidence after taking the lead, then grew all edgy once more after Jack Collison should have steadied them with a second goal just before the interval. They scarcely threatened again until a series of counter-attacks in the last 10 minutes brought a second goal, headed by Radoslav Kovac.
Throughout it all their most impressive performer was Scott Parker, perpetual motion in midfield despite – or perhaps because of – losing his midfield partner Mark Noble early on. Although Gianfranco Zola insists nobody need be sold, West Ham supporters will remain concerned until the transfer window has passed with Parker and his fellow England internationals Robert Green and Matthew Upson still on board. Some of the imports, meanwhile, are settling down; Alessandro Diamanti, scoring for the third successive game, impressed after moving to the left of midfield after Noble's departure, and Zola had particular praise for another midfielder, Kovac, from the Czech Republic.
"I rated this as a six-point game," Zola said. "It was so important for the table and for morale. The boys showed a lot of character and it will be a big boost for everyone."
A timely one too, propelling them out of the bottom three ahead of tomorrow's derby at Tottenham.
Grant was hoping for a similar benefit from last week's victory over Liverpool, but as well as the psychological damage from this defeat he faces the prospect of losing four players from his first-team squad to the African Cup of Nations. He will discover this week whether the club's transfer embargo will be lifted, enabling them to sign much-needed reinforcements over the next month. "Everything is possible," he said of the struggle at the bottom. "We have the quality to win."
More remarkable was his assertion that Portsmouth "need more aggression". In a poor first half, Michael Brown and Aruna Dindane could each have been sent off but escaped with yellow cards. Brown had already been booked for a wild lunge at Parker when he tripped the substitute Luis Jimenez. Diamanti scored with ease from the penalty spot.
Just before the interval, Parker's cross offered Collison a wonderful opportunity to calm everyone down but the Wales international dragged his shot wide. Right at the start of the second half the excellent Asmir Begovic brought off the save of the game, one-handed, as Diamanti's shot deflected up off Steve Finnan, but that was the last seen of West Ham as an attacking force for some half an hour.
The appearance of Kevin-Prince Boateng as a half-time substitute transformed Portsmouth, who were further improved by bringing on the ageless Kanu. One typically deft touch almost set up Frédéric Piquionne, who was then denied by Robert Green, after surging past James Tomkins.
With the crowd reflecting the team's edginess rather than supplying the full-blooded support requested of them, West Ham held on, then clambered back into the game with a series of counters. Begovic again saved well, this time from Collison, Parker played Valon Behrami in to shoot a fraction wide and from a right-wing corner Kovac rose to confirm a vital victory. There may have been murder in the Queen Vic this Christmas, but it has been a happier time for the real East Enders.
Referee: Lee Probert
Man of the match: Parker
Match rating: 6/10