Somdev Devvarman and Sania Mirza registered convincing straight sets victories over their respective higher-ranked opponents in the first round of the Sony Ericsson Open, in Miami, USA.Ranked 73 in ATP charts, Somdev thrashed world number 47 Potito Starace of Italy 6-2 6-4 in his opening round of the ATP Masters event.While Sania, ranked 99, defeated Spanish world number 62 Arantxa Parra Santonja 6-2 6-4 in WTA premier event. Sania has a tough second round ahead as she is up against 24th seed Russian Maria Kirilenko. Somdev will clash with Canadian world number 34 Milos Raonic, seeded 31, in his second round.