By 1248 GMT, the rouble was down 0.7% against the dollar at 78.18 RUBUTSTN=MCX, reaching its weakest mark since Oct. 7.
It had lost 0.3% to trade at 91.51 versus the euro EURRUBTN=MCX, a one-week low.
Brent crude oil LCOc1, a global benchmark for Russia's main export, was down 3.1% at $41.96 a barrel.
Rising coronavirus cases at home and abroad hurt Russian assets, with new lockdown restrictions and pessimism over U.S. stimulus measures reducing risk appetite.
The Russian market was poised for a retreat, Alfa Bank said in a note: "Market sentiment has shifted to risk-off and investors are starting to book profit after the recent rally."
As well as sanctions, several geopolitical risks have plagued the rouble in recent weeks, including turmoil in neighbouring Belarus, political unrest in Kyrgyzstan, and a military conflict in the South Caucasus.
Russia on Thursday recorded a record daily increase in coronavirus deaths and more than 13,000 new cases as a second COVID-19 wave threatened the country's economic revival.
Domestically, Russia's central bank was seeking to limit downward pressure on the rouble by selling around 8.6 billion roubles ($110.4 million) worth of foreign currency a day.
Russian stock indexes were down, near month-long lows.
The dollar-denominated RTS index .IRTS was down 2% to 1,136.6 points, just shy of a five-month trough. The rouble-based MOEX Russian index .IMOEX was 1.2% lower at 2,821.1 points.
Real estate developer Samolet said it was eyeing an initial public offering on the Moscow Exchange of about 5.1% of its shares later this year.
For Russian equities guide see RU/EQUITY
For Russian treasury bonds see 0#RUTSY=MM
($1 = 77.8900 roubles)
(Reporting by Alexander Marrow; Editing by Larry King and Alex Richardson)
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