The move comes ahead of the RBI's announcement on lending rates on 5 December. The RBI's monetary policy committee (MPC) will meet between 3-5 December to review the interest rates.
CRISIL's revision, which is among the lowest after Japanese brokerage Nomura's 4.7 percent forecast, comes within days of the official data showing a further slip in the second-quarter growth to 4.5 percent. This leaves the first half (April-September) growth at 4.75 percent, a multi-year low.
"Key short-term indicators like industrial production, merchandise exports, bank credit offtake, tax mop-ups, freight movement, and electricity production, all point to a weakening growth momentum," CRISIL said in a research report.
However, it expects a "mild" pick-up in growth in the second half.
Growth in the second half of 2019-20 will go up to 5.5 percent, up from the 4.75 percent in the first half, the agency said.
In October's policy review, the RBI revised downwards its estimate for GDP growth for the current fiscal to 6.1 percent from 6.9 percent estimated earlier.
The central bank is widely expected to slash rates for the sixth time on 5 December. In five reductions so far in 2019, interest rates have been lowered by a total of 135 basis points over concerns that growth momentum is slowing down and also to try to boost liquidity in the financial system.
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