Breach of rising trend line drawn from Feb low and June low coupled with a falling tops formation since Aug 15 suggests the index is more likely to breach key support of 17935 (trend line drawn from Sep 12 low and Oct 13 low).
A daily close below 17,935 would confirm trend reversal suggested by breach of rising trend line.
On the higher side, only a daily close above falling trendline would restore bullish sentiment.