Vinnie Samways secured Walsall a first away league win of the season as his stunning free-kick caught Reading cold at the Madejski Stadium.
The former Tottenham midfielder curled home from 20 yards inside the first four minutes to hand Steve Coppell his first defeat as Reading manager.
But Reading keeper Marcus Hahnemann will take much of the blame for the Walsall winner as he was caught out of position and beaten at his near post by Samways' shot.
Steve Brown's foul just outside the penalty area gave him a sight of goal and, as Reading's defence pushed out looking for offside and Hahnemann positioned himself for a cross, Samways curled a shot into the top right-hand corner.
Reading had little answer to the early setback in the opening half an hour but finally came to life in the ten minutes leading up to half-time.
Lively winger John Salako saw a shot on the turn fly straight at Jimmy Walker from the edge of the box.
Then leading scorer Nicky Forster flashed a low effort just wide of the far post after Steve Sidwell had sent him clear.
Forster was denied by Walker early in the second half, the Walsall keeper diving at his feet after Sidwell's pass had been cleverly dummied by Shaun Goater.
And winger Scott Murray went close when he latched on to a Forster pass and fired a shot into the side-netting from 20 yards.
Forster was desperately unlucky not to level 16 minutes from time when he headed over from close range after Goater had flicked on a right-wing cross from Salako.
But Walsall held firm at the back, although they did have to survive late penalty claims when Adi Williams' flick seemed to deflect off substitute Jamie Lawrence and onto the arm of Darren Wrack.