:Americans Jessica Pegula and Coco Gauff secured straight-sets victories over Canadians on Thursday to book their spots in the third round of the Miami Open, while Indian Wells champion Elena Rybakina battled to a win over Anna Kalinskaya.Third seed Pegula beat qualifier Katherine Sebov 6-3 6-1 and will next face fellow American Danielle Collins, while sixth seed Gauff eased past Rebecca Marino 6-4 6-3 to set up a battle with Russia's Anastasia Potapova.Pegula, a semi-finalist last year in Miami who lives about 40 minutes away from the tournament venue, converted five of her nine break point opportunities and found her groove as her first career match against Sebov wore on."(I) fought through some tricky moments in the first set but then I think I started to free up after that," Pegula said in her on-court interview.Gauff, who also resides in Southeast Florida and is coming off a run to the quarter-finals in Indian Wells, converted five of her nine break point chances and twice came back from a break down in the second set."Playing at home is something I look forward to but it's also a little extra pressure because you know everybody wants you to do well here," Gauff said.With the victory, the 19-year-old Gauff broke a stalemate with Anastasia Pavlyuchenkova and now holds the record for most wins (34) at WTA 1000 events before turning 20.In other second-round action, Belgian Elise Mertens beat Russian eighth seed Daria Kasatkina while Latvian 24th seed Jelena Ostapenko, Spanish 21st seed Paula Badosa and China's Zheng Qinwen, the 23rd seed, also advanced.RYBAKINA EYES 'SUNSHINE DOUBLE'Later on Thursday, Wimbledon champion Rybakina, fresh off her triumph at Indian Wells, closed out the evening session with a hard-fought