American teenage sensation Coco Gauff beat Czech doubles specialist Katerina Siniakova in straight sets to clinch a second-round spot at the Ostrava Open WTA tournament on Tuesday.
After both players dropped serve three times in the first set, the 16-year-old world number 55 gained the decisive seventh break.
The second set went with serve until the tenth game when Gauff broke to take the match 7-5, 6-4.
Gauff squandered her first three match points but the Czech hit the net on the fourth to bow out.
"Today was tough, I wasn't really playing my best," Gauff told Czech Television in an arena empty because of coronavirus restrictions.
"I just kind of had to fight through," added Gauff, who had beaten Slovakia's Jana Cepelova and Irina-Camelia Begu of Romania in qualifying.
Gauff will face third-seeded Aryna Sabalenka of Belarus, the world number 12, in the second round.
Qualifiers were on a spree in the eastern Czech steel hub on Tuesday.
Daria Kasatkina of Russia saw off sixth seed Elena Rybakina of Kazakhstan 6-2, 3-6, 6-3, while her compatriot Veronika Kudermetova upset Croatia's Donna Vekic 6-2, 6-4.
The tournament's top seed Elina Svitolina, the world number five, plays her first match against Maria Sakkari on Wednesday after being granted a bye for the first round.