Villa snatches win versus Reading
The Belgium international ended a four-game run without a goal when he headed home an Ashley Westwood corner with 10 minutes remaining.
Villa's third win of the season moved them out of the Barclays Premier League bottom three in front of their lowest home league gate - 28,692 - for six years.
The game was not a classic but Villa deserved the three points after enjoying the bulk of possession and looking the more threatening.
Bent was left out of Lambert's matchday plans for the second successive game with rookie striker Jordan Bowery again preferred on the substitutes' bench.
Villa denied former Tottenham striker Bent had left the ground after being left out and he watched the game from an executive box.
Bent had already lost his place in the starting line-up to Benteke before being sidelined with an ankle injury. But it is a mystery why Lambert is not prepared to include in his final 18 a player who was signed two years ago to score the goals to keep Villa in the top flight.
Villa, who fielded eight players aged 23 or under, enjoyed the bulk of the possession and the recalled Brett Holman impressed in central midfield.
Reading looked more solid than when conceding sloppy goals in Saturday's 3-2 defeat at Wigan but seldom posed a threat to a solid Villa back four in which Ciaran Clark again impressed.
Hal Robson-Kanu had the first attempt on goal after being found in space by Jason Roberts but he curled his shot wide of the far post.
Holman exchanged passes with Andreas Weimann but his run into the box proved to no avail as the return ball from the Austrian striker was over-hit.
Villa midfielder Barry Bannan played his side into trouble when dispossessed by Shaun Cummings.
He released Royals skipper Jobi McAnuff but Adam Le Fondre could not make as full contact on his ball across the danger area.
The first meaningful save came when Reading keeper Adam Federici went down to his right to smother a low Benteke shot after the impressive Holman had supplied the low cross.
Villa were forced to make a change after 24 minutes when left-back Enda Stevens limped out of the action to be replaced by Eric Lichaj.
Weimann squandered a golden chance to break the deadlock three minutes later. Benteke created a yard of space for himself inside the box before finding Weimann unmarked at the far side of the six yard box but he fired high over the bar.
The recalled Nathan Baker then got on the end of an inswinging Bannan corner but sent his downward header past the post.
Villa continued to press and Clark glanced a header wide from another Bannan cross.
Baker flicked a Bannan corner wide at the start of the second half and Clark was not far off target with a header from the same source.
But Reading came more into the game and Roberts cut inside before seeing his shot blocked by the legs of Brad Guzan. Clark became the first player to be booked for bringing down Roberts.
The game appeared to be heading for a stalemate but with 10 minutes left Benteke settled the issue. Lambert's £7million summer signing from Genk climbed above the Royals defenSe and his downward header flew past Federici.
The Villa boss could not contain his delight but knows there is still much work to be done before his young side banish fears of the drop.