Zak Rudden's first-half strike sealed a 1-0 victory for Plymouth at Cheltenham.
The 19-year-old Rangers loan striker fired in his second League Two goal of the campaign in the 33rd minute after Antoni Sarcevic touched a fine ball from George Cooper to him in the six-yard box.
Plymouth's Billy Clarke clipped the top of the bar in the 14th minute with a long-range volley.
Alex Addai was Cheltenham's main threat, firing over from 20 yards early on and then reaching a low ball from Gavin Reilly six minutes before the break, but his effort was wide of the left post.
Rudden forced Scott Flinders into a save before the break.
The home side's best chance for a leveller fell to George Lloyd after good work from Ryan Broom.
The substitute blazed over the bar in the 82nd minute as Cheltenham fell to their third League Two home defeat of the calendar year.