Indian equity benchmarks Sensex and Nifty50 are likely to start Tuesday's session on a positive note tracking gains across Asian markets despite a sluggish session on Wall Street overnight. At 8:21 am, Nifty futures trading on Singapore Exchange -- an early indicator of NSE's Nifty50 benchmark index in India -- were up 55 points or 0.3 percent at 18,194, having risen as much as 64 points earlier in the day.