At 1010 GMT, the rouble was 0.3pc weaker against the dollar at 64.89, its weakest level since Sept. 12.
Versus the euro, the rouble lost 0.2pc to trade at 70.87.
"Risks for the rouble are skewed towards its weakening in the course of the next month," Nordea Bank said in a note.
The rouble eased versus the dollar as global political uncertainty and fears over a widening of the China-U.S trade war kept investors in safe harbours, sending oil prices lower.
Expectations that the Russian Finance Ministry will increase its daily purchases of foreign currency in October also add pressure on the rouble, deprived of support from monthly tax payments that usually add to demand for the Russian currency.
Market activity this week is likely to be below average as Chinese markets will be closed for public holidays for one week starting from Tuesday.
Prices for oil, Russia's main export, slipped as China's economic outlook remained weak even as manufacturing data improved.
Brent crude oil was down 1.4pc at $61.02 a barrel.
The dollar-denominated RTS index was down 1.0pc to 1,333.9 points.
The rouble-based MOEX Russian index was 0.4pc lower at 2,746.8 points.