At 1500, GMT the rand was 0.43pc weaker at 14.4280 per dollar compared with an opening level of 14.3860.
The rand rallied close to 3.5pc in the previous week and on Monday was still near its strongest since Aug. 1, but with offshore risks building and volumes relatively light heading into Christmas holidays, the momentum faded on Tuesday.
Reports on Tuesday that new British Prime Minister Boris Johnson was ready to push for a hard exit from the monetary union scuppered some of the early-session risk appetite that had kept the rand and its emerging market peers bid.
With only monthly government budget balance data on the local calendar this week, the rand is set be swayed by offshore events, although traders will have one eye on developments in energy policy following last week's nationwide blackouts.
On Tuesday, Energy Minister Gwede Mantashe vowed to keep burning coal to generate electricity, even as the continent's biggest greenhouse gas emitter adopts more renewable-energy sources to meet its commitments on climate change.
Bonds gained, with the yield on the benchmark 2026 government issue down 3 basis points to 8.29pc.
In equities, stocks climbed alongside other emerging-market shares, on hopes an initial U.S-China trade deal will mark a turning point in one of the major risks to global economic growth.
State-owned power utility Eskom announced that there would be no rolling power cuts on Tuesday and a low probability of any during the week, providing relief to retailers, who were hit hard by the blackouts.
The benchmark JSE Top-40 Index was up 1.23pc to 51,122.19 points.
The broader All-Share Index rose 1.27pc to 57,467.44 points.
Energy and chemicals company Sasol soared 11.92pc to 307.01 rand, reaching the top of the blue-chip index, after announcing that the Lake Charles Chemicals Project ethane cracker is increasing production rates following the successful replacement of the acetylene reactor catalyst.
Following Sasol was retailer Mr Price Group, which rose 5.32pc to 193.19 rand, and mining company Anglo American Platinum, which rose 4.99pc to 1,383 rand.