At the pre-opening bell, the frontline index S&P BSE Sensex opened in green with a gain of 117.15 points or 0.14%. On the sectoral front, metals jumped by 0.34%, power zoomed by 0.35% and auto soared by 0.33%. Meanwhile, Reliance Power Ltd, Nazara Technologies Ltd and Sapphire Foods India Ltd emerged as the top gainers in the pre-opening session today.