Saturday's Suncorp Stadium clash was a dour affair for almost an hour, before a Carter Gordon double and another dazzling five-pointer for Isaac Henry got the Reds home 26-17.
Gordon hopped over a would-be tackler in broken play and showed impressive speed to burn around Harry Potter for the match-winner from 55 metres out with six minutes to play.
Henry linked up with rampaging winger Filipo Daugunu, who had weaved through traffic after substitute Treyvon Pritchard's earlier line-break had shaken things up.
Earlier, Gordon finished a play set up by another line-break and a flick pass from in-form fullback Jock Campbell.
Gordon's bomb in the first half led to a Harry Wilson try as the Test flyhalf, who scored last week's match-winner against the ACT Brumbies, again showed his wares after a stint in the NRL.
Scores were locked 7-7 at halftime before impressive Tahs hooker Ioane Moananu found the line.
Potter also scored to put the visitors up by five before the Reds came to life.
The hosts improved to 3-1 before next Saturday's trip to Fiji, where they've never won, while the Waratahs dropped to 2-2 but showed far more resolve than in their 59-19 loss to the Hurricanes a week ago.
Source: super.rugby
