Juventus appeared to be sailing through to the knockout phase as Group H winners after Ronaldo's glorious strike against his former club, but substitute Juan Mata drew the visitors level and an Alex Sandro own goal completed a remarkable finish.
Juve went agonisingly close to the breakthrough just past the half-hour - Ronaldo picking out Khedira in the centre of the box with a cut-back, but the midfielder's first-time low shot hit the post.
Ronaldo finally ended United's resistance just past the hour, however, racing on to Bonucci's long-range pass and sending an unstoppable volley beyond De Gea after the ball dropped over his shoulder.
Although Juventus ended up losing the tie, Cristiano Ronaldo has finally scored his first Champions League goal with Juventus with his 11th shot, thus ending a 454-minute drought in the competition.
Catch all the highlights of how the Portuguese fared against his former team!