The Bombay Stock Exchange benchmark Sensex shot up by nearly 142 points to 20,307 in the opening trade on Sunday.The Sensex was trading at 20,373 up by over 207 points a short while ago. Analysts said the gain in Sensex is due to strong capital inflows by foreign funds and firm Asian markets.In the Asian region, the Hong Kong's Hang Seng index was up by 0.33 per cent, while Japanese Nikkei gained 0.10 per cent in the morning trade.