The rupee on Monday slipped below the 66-level by tumbling 74 paise, or 1.11%, at 66.50 against dollar in early trade on strong demand for the American currency from banks and importers.
Gains in the dollar against major global currencies following surge in US jobs last month put pressure on the Indian unit, dealers said.
Besides, a lower opening in domestic equity markets, weighed on the rupee, they added. The rupee had closed one paise lower at 65.76 against dollar at the Interbank Foreign Exchange on Friday.
Meanwhile, the benchmark BSE Sensex dipped below the 26,000-mark by slumping 608.34 points, or 2.31%, at 25,656.90 in early trade.