It was tight, it was bad-tempered, it was nervy and the huge roar that greeted Michael Oliver's final whistle demonstrated how significant this victory could be in Reading's attempt to stay up. This, after all, was only their second victory of the season and, while there was an element of fortune about it, if Reading can maintain their new-found defensive organisation, they may yet pull off what would be one of the great escapes.
For West Ham, there was disbelief at letting the points slip away and concern about a third defeat in four matches. They have not won since beating Chelsea at the start of December. Or, to put it another way, they have not won since Mohamed Diamé, reportedly the subject of a bid from Queens Park Rangers, injured his hamstring three weeks ago. To compound the frustration for Sam Allardyce, James Collins and Kevin Nolan both picked up bookings that will rule them out for the visit of Norwich City on New Year's Day.
In truth, West Ham were their own worst enemies. For too long they were more intent on settling old scores with Jimmy Kébé dating back to this fixture last season, wasted chances once they got going and gifted Reading their winner after five minutes.
There appeared to be no danger when a loose ball fell to Collins 40 yards from his own goal. However when he tried to play a backpass to his goalkeeper, Jussi Jaaskelainen, a horrible scuff allowed Pavel Pogrebnyak to run clear and give Reading the lead with a composed finish. Collins was jeered mercilessly by the home supporters for the rest of the match. Perhaps by the West Ham fans, too.
"It was a real resilient performance," Brian McDermott said of his Reading side. "It was a physical game and I think we matched them. The goal that Pavel scored was a really good finish. If he does get the chance, he hits the target."
The foundation for Reading's recent improvement has been tightening up at the back but 85 minutes still felt like a long time to hold on and once West Ham settled, Adam Federici had to be in inspired form to preserve the lead. Happily for Reading, he was. West Ham's delivery from wide areas was mostly appalling but when Nolan's cross was met by a looping header from Winston Reid midway through the first half, Federici tipped it over.
As the rain became heavier in the second half, so the tension increased. The pressure from West Ham intensified and as much as Reading's supporters bellowed encouragement to their side, there was too often nowhere for them to go.
Jem Karacan crashed a shot against the crossbar from the edge of the area and Kébé slashed the rebound wide but the most threatening moments belonged to West Ham. Carlton Cole headed over, before Jack Collison's skidding shot from the right, heading towards the far corner, was pushed away by Federici.
However Federici should have been given no chance with seven minutes remaining when Jarvis's cross from the left found Ricardo Vaz Tê, who came off the bench to make his first appearance since dislocating his shoulder in October, all alone at the far post. The equaliser looked inevitable but incredibly he put his header wide from inside the six-yard box.
"James Collins makes a basic error and Vaz Tê misses the easiest chance I've ever seen in a Premier League football match," Allardyce said. "Because we made those mistakes, we got nothing out of the game."
After last week's controversial defeat against Manchester City, Reading will argue it is about time they got some luck.