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After one round of 2018 French Open action, two of the biggest names in women's competition were already out of contention.

While two-time Wimbledon champion and French Open favorite Petra Kvitova rebounded on her redemptive post-knife attack journey to top Veronica Cepede Royg and move onto the second round, the courts weren't as kind to Jelena Ostapenko and Venus Williams on Sunday.

Ostapenko, the 20-year-old Latvian breakout who captured the women's singles title in 2017 and became the first unseeded women's champ since 1933, couldn't muster as much magic against 66th-ranked Kateryna Kozlova on the first day of the Open. Undone by 48 unforced errors and more than a dozen double faults against Kozlova, she lost 7-5, 6-3 at Roland Garros, where Kozlova seemingly played the low-expectations role of 2017's Ostapenko, who took the Open by storm during her run to a title.

For Williams, the five-time Wimbledon champion and four-time Olympic gold medalist, things weren't much better, as the 37-year-old superstar lost 6-4, 7-5 to China's Qiang Wang, who entered the Open ranked 91st. She's still scheduled to team up with her sister, Serena, for women's doubles, but on her own, the older sibling is already eliminated from singles despite a No. 9 ranking among American contenders. This defeat comes just months after she was ousted in the opening round of January's Australian Open.

Williams' sister, Serena, opened as one of the oddsmakers' favorites to take this year's women's singles championship.