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At 0705 GMT, the rand fell 0.34% to 14.2125 per dollar.
State power firm Eskom financial results for the 2018/19 financial year are expected to show a large loss and steep increase in debt.
Rating agencies Fitch and Moody's last week both warned about fiscal pressure on South Africa and highlighted Eskom as a risk, piling pressure on the currency.
Statistics South Africa will also release second-quarter unemployment figures on Tuesday.
In fixed income, the yield on the benchmark government bond due in 2026 was up 3 basis points to 8.345%.
Stocks opened slightly weaker with the All-share index down 0.14% to 57,954 points, while the Top-40 index I dipped 0.05% to 51,950 points.