At 0730 GMT, the rouble was 0.1% stronger against the dollar at 63.39 and had gained 0.2% to trade at 70.59 versus the euro.

U.S. policymakers are widely expected to cut rates by a quarter percentage point on Wednesday, although some investors see chances of a half percentage point reduction.

If the Fed indicates a high probability of a full rate cut cycle, which is three or more cuts in a row, this would be a positive signal for all emerging currencies, said Mikhail Poddubsky, an analyst at Promsvyazbank.

Lower U.S. rates raise investors' interest in other currencies and market instruments that offer higher yields.

Locally, the Russian Finance Ministry was in focus as it was about to announce details of its weekly OFZ bond auctions due on Wednesday.

Oil prices rose for a fourth day on Tuesday on optimism that the U.S. rate cut would support fuel demand growth.

Brent crude oil, a global benchmark for Russia's main export, was up 0.4% at $64.11 a barrel.

Russian stock indexes were mixed. The dollar-denominated RTS index was up 0.05% to 1,354 points. The rouble-based MOEX Russian index was 0.17% lower at 2,723 points.

Shares in Yandex, Russia's leading internet firm, outperformed the broader market by climbing 1.4% higher after the government criticized a draft law on limiting foreign ownership in major Russian IT companies, which had previously sent Yandex shares tumbling.