American teenager Amanda Anisimova, fresh off an impressive run at Indian Wells, beat China's Wang Qiang 6-3, 1-6, 6-2 at the Miami Open on Tuesday to set up a second round clash with Spanish third seed Garbine Muguruza.
The 16-year-old wild card, who had never won a WTA main-draw match until this month's BNP Paribas Open where she reached the fourth round, broke the world number 53 five times during a 98-minute match in which she committed six double faults.
Next up for Anisimova, ranked 130th in the world, is Wimbledon champion Muguruza, who will be eager to get back to competition after falling at the first hurdle in Indian Wells.
Brazilian Beatriz Haddad Maia overcame some early pressure to defeat Briton Heather Watson 7-6(3), 6-2. Watson had a chance to serve for the opening set but squandered it and then allowed the Brazilian to run away with the match.
Haddad Maia will next face No. 31 seed Zhang Shuai.
Australia's Ajla Tomljanovic looked headed for an early exit when she fell behind 4-0 in the deciding set against Ukraine's Lesia Tsurenko but the Croatian-born world number 90 reeled off seven of the next eight games to prevail 3-6, 6-4, 7-5.
American wild card Bernarda Pera advanced when she stunned Spanish world number 68 Lara Arruabarrena 7-5, 6-4 to set up a second-round match with Belgian 22rd seed Elise Mertens.
Estonia's Kaia Kanepi was leading Christina McHale 3-1 but retired 31 minutes into the match, gifting the American passage into the second round where she will face Czech Barbora Strycova.
Also advancing on the first day of the main draw in Miami were Belgians Kirsten Flipkens and Alison Van Uytvanck, Swede Johanna Larsson, Hungary's Timea Babos, Belarusian Aliaksandra Sasnovich and American wild card Claire Liu.
Tomic's return to court ends early in France
Bernard Tomic's bid to kick-start his career after slipping to 181st in the world hit a speed bump on Tuesday when the 25-year-old Australian was knocked out in the first round of a second-tier tournament in France.
Tomic, once touted as a top-10 player, was beaten 6-2, 2-6, 6-4 by France's Antonie Hoang at the tournament in Lille.
It was his first outing since losing in the third round of qualifying for the Australian Open in Melbourne in January, a defeat that then saw him snap at reporters.
That setback followed a forgettable 2017 season, during which he declared himself "bored" by tennis at Wimbledon and spoke of feeling "trapped" during media interviews.
Tomic, who was a contestant in a reality television show after the Australian Open, then put himself at loggerheads with Davis Cup captain Lleyton Hewitt by saying Australia would not win the title if he was not picked.
Hewitt said it was unlikely Tomic would play under him again.
Tomic, however, seemed to have recognised a rethink was in order last month when he said that he had wasted 2017. He resumed training and was keen to rebuild his career on the secondary Challenger circuit before looking to rejoin the main ATP Tour in April.
"I'm ready to challenge myself and hopefully in the next year I can be well inside the top 30," he told News Corp in February. "But I'm going to have to work hard."