In a hard-fought contest, a set-piece undid the Royals as the Midlands side have their Belgian international to thank after his goal moves them out of the relegation zone
In a game full of endeavour but bereft of real quality, it was a Villa set-piece that ultimately consigned the Royals to at least another few days in the relegation zone, as Benteke powered home from an Ashley Westwood corner.
Lambert made two changes from the side that earned a point against Arsenal, bringing in Nathan Baker for injured captain Ron Vlaar as Brett Holman also came in at the expense of Karim El Ahmadi. For the fifth game in succession, Darren Bent failed to make the bench.
Reading, meanwhile, made two defensive changes from the side that lost against Wigan with Shaun Cummings and Adrian Mariappa replacing Chris Gunter and Kaspars Gorkss.
A lively opening meant it was just nine minutes before the first clear-cut chance fell the way of the visitors; a Jobi McAnuff cross producing a Hal Robson-Kanu toe-poke that forced Brad Guzan into an excellent point-blank save.
An even better chance fell Benteke's way 10 minutes later as a Jay Tabb cross found him in the area, only for the Belgian's side-footed effort to be saved with aplomb by Adam Federici.
It was Benteke's turn to play provider next as he squared a cross to Andreas Weimann who, six yards out, could only blaze way over with the strike.
Half-chances continued to fall both sides' way in the second half, with Holman first firing wide for the hosts before both Adam Le Fondre and Ciaran Clark failed to capitalise from free headers.
The end-to-end football continued as Guzan produced another decent save to deny a Jason Roberts effort with 65 minutes gone.
Both sides continued to battle without much reward and it was the 80th minute before the stalemate was finally broken as, following a Westwood corner, Benteke powerfully rose above Morrison and thumped his header emphatically home from eight yards out.
Reading were unable to mount a comeback of any substance, the only clear-cut chance falling to substitute Noel Hunt, who could only head into Guzan's grateful arms.