Chris Brandon gave Town a dream start when he hammered a 20-yard effort into the bottom corner after Rovers had failed to clear their lines following a second minute corner.
Doncaster then dominated for a 20-minute spell but were unable to get the ball in the net. Tim Ryan had a cracking 30-yard shot tipped round the post and four minutes later Guy blasted over the top from close range.
Huddersfield gained control just before the interval and home keeper Andy Warrington did well to parry a swerving shot from Jon Worthington when he was unsighted in the 28th minute.
Warrington came to the rescue again to save one-handed after Danny Schofield had cut inside and dribbled past a couple of defenders but there was no stopping Worthington when he made it 2-0 just before the interval with a thunderbolt from out of the blue.
Rovers came out for the second half with all guns blazing and Ryan had the keeper at full stretch again with a 20-yard shot in the 48th minute.
The home side pulled one back with a 63rd minute goal from Michael McIndoe after visiting keeper Paul Rachubka had brought down Guy.
Neil Roberts missed a good chance to equalise in the 65th minute and Rachubka saved from Dave Mulligan five minutes later.
Guy was dismissed on 74 minutes for pushing Tom Clarke in the face but Rovers still had a chance to equalise when McIndoe raced clean through only to be foiled by a brilliant save 12 minutes from time.