Paul Lambert has parroted it like a mantra throughout the season. "We'll be fine," the Aston Villa manager has said. Here is a Glaswegian of intensity and the impression has been that if he says it sufficiently, he can force it to happen; that the strength of his personality can will an inexperienced squad into prolonging the club's 25-year membership of the elite.

This victory, only a second in 12 Premier League matches, brought substance to the belief. It was a long way from being handsome and there was the sense that Villa were clinging on in the second half but it did nothing to dilute the tonic. Lambert's men survived their latest self-inflicted wound, a darkly comic own goal from Nathan Baker, and a few borderline decisions to pull clear of the relegation places.

Reading were left to nurse bitter regret, and not only for their dreadful defending in the first half. They had the chances, as Brian McDermott noted, to have taken "the decision-maker out of the game", in other words, the officials, who ignored two penalty appeals and ruled out for offside what would have been a second-half equaliser from Noel Hunt. Reading left their shooting boots in the dressing room.

Commendably, McDermott did not dwell on the decisions, despite being convinced that Hunt had been barged over in the early running by Brad Guzan and wondering whether the substitute Nick Blackman might had got something from an injury-time tangle inside the area with Yacouba Sylla, Villa's full Premier League debutant. But McDermott could not hide the pain of the defeat that pressed his team to joint-bottom of the table with Queens Park Rangers. Next up for them, after four straight league defeats, are trips to Manchester United and Arsenal.

"There were inches in the offside decision … I don't know if it was offside or not but the referee has got good eyes to see that," McDermott said. "The result is disappointing, to say the least. It certainly hurts. We didn't kick on at 1-0 and that's cost us."

Lambert felt that Villa's spirit was epitomised by Baker who, according to him, recovered in "exceptional" fashion from his aberration. Villa's defensive wobbles have been well documented but this was a new low. After Jobi McAnuff had beaten Matthew Lowton to a cross from the left and Hope Akpan had flicked goalwards, Baker, on the far post, swung his right foot to clear only to miss, see the ball hit his standing foot and roll, almost apologetically, into the net.

Yet Reading found a way to trail at the interval and depart to a chorus of boos from their supporters. They lost their focus completely after Baker's gift and when Andreas Weimann stole on to Ashley Westwood's pass to cut back from the right, three Reading defenders had toddled like lemmings towards the goalline. Christian Benteke, who had dropped off, shot home with the aid of a deflection off Stephen Kelly.

Worse was to come for Reading, and it was not just the timing of Villa's second that hurt. Kelly's attempted clearance from Weimann's cross was sliced high and when Lowton won a key header, Barry Bannan's instinctive shot came back off the post. Reading froze but Gabby Agbonlahor did not. Lambert described the finish, lashed into the top corner, as "absolutely world-class."

Reading had flickered at the outset, with Adam Le Fondre's header forcing Guzan into a reflex save and the hosts were incensed when the Villa goalkeeper bundled into Hunt inside the area. But Villa, set up with a tight midfield three, had fashioned a foothold before the burst of goals. Benteke headed against the crossbar and Weimann dragged a good chance wide on the counter.

Agbonlahor's goal felt as though it deserved to be decisive – Villa's build-up had featured 20-plus passes before the Kelly slice – but Lambert's men lived on their nerves in the second half. The biggest call was that for offside. McAnuff's cross bypassed Le Fondre in the middle and Hunt converted at the back post only to scream injustice when the assistant referee flagged. Le Fondre, who was central to the action, and Hunt might have been fractionally in front of the last man. Everyone was agreed that it was fiendishly tight.

The Reading crowd is edgy, and they jeered again when McDermott substituted Akpan and Hunt before the hour but not the disappointing Mikele Leigertwood. There were cheers when the midfielder was eventually withdrawn. But Reading carried the fight. Hal Robson-Kanu wasted a glorious chance, as he would towards the very end, and Blackman headed at Guzan.

Agbonhalor and the substitute Charles N'Zogbia had the chances to make the closing stages more comfortable for Villa but they do not trade in comfort. The wild scenes among the travelling fans upon the final whistle spoke of joy and relief.