Top seed Ash Barty completed a 6-4 6-2 win over Zheng Saisai in her opening match of this year's Wimbledon. The French Open champion and world number one was given a decent work-out by the world number 43 Zheng before sealing victory in one hour and 16 minutes on Centre Court. Barty's best at the All England club was a quarter-final spot a year ago. The Australian will face Belgium's Alison Van Uytvanck in the second round. "The first round is always tough and it took a bit of time to get used to conditions on that beautiful court which I have a lot of happy memories on. It took some time to adjust but I got there in the end," said Barty. Garbine Muguruza, Wimbledon champion in 2017, was knocked out in the first round, losing 6-4 6-4 to Beatriz Haddad Maia. The world number 27 was dumped out by the 23-year-old Brazilian, who has never won a career singles title and is ranked 121 in the world. The defeat added to a barren spell at the majors for the 25-year-old Muguruza, who has not been past the fourth round in any of the last five Grand Slams. The defeat also continued a patchy season for the 25-year-old Spaniard who has been past the quarter-final at only one tournament, when she won in Monterrey in April. American ninth seed Sloane Stephens, who had crashed out in the opening round in the previous two years, breezed past Switzerland's Timea Bacsinszky 6-2 6-4 in her tournament opener. Also advancing to the second round were Belgium's Elise Mertens, who beat Fiona Ferro 6-2 6-0 and China's Wang Qiang who eased past Vera Lapko 6-2 6-2. Lesia Tsurenko, the 32nd seed, fell 6-3 6-2 to Barbora Strycova.