Mumbai, Mar 31 (UNI) Mumbai Indians won the toss and opted to field against Kolkata Knight Riders in their high-octane Indian Premier League (IPL) clash at Wankhede Stadium here on Sunday. The night also marked a special occasion for Mumbai’s new pace sensation Ashwani Kumar, who made his IPL debut, while KKR’s star all-rounder Sunil Narine returned to the playing XI.