Paris - Second seed Caroline Wozniacki held off the challenge of American Danielle Collins to ease through their French Open first-round match 7-6 (7/2) 6-1 on Monday.
The Australian Open champion has never reached the semi-finals at Roland Garros, but after a tight first set, she was too strong for surprise Miami semi-finalist Collins, who was making her French Open debut.
The 27-year-old Dane will take over from Simona Halep as world number one if she lifts the title a week on Saturday.
Wozniacki will next face Spanish qualifier and world number 219 Georgina Garcia Perez for a place in the last 32.
Results from day two of the French Open at Roland Garros on Monday (x denotes seeding):
Men
1st round
Marco Trungelliti (ARG) bt Bernard Tomic (AUS) 6-4, 5-7, 6-4, 6-4
Marco Cecchinato (ITA) bt Marius Copil (ROM) 2-6, 6-7 (4/7), 7-5, 6-2, 10-8
Santiago Giraldo (COL) bt Marcos Baghdatis (CYP) 3-6, 3-4 -- retired
Novak Djokovic (SRB x20) bt Rogrio Dutra Silva (BRA) 6-3, 6-4, 6-4
Stefanos Tsitsipas (GRE) bt Carlos Taberner (ESP) 7-5, 6-7 (5/7), 6-4, 6-3
Ernests Gulbis (LAT) bt Gilles Muller (LUX x29) 2-6, 6-4, 6-4, 6-3
Benot Paire (FRA) bt Roberto Carballs (ESP) 6-3, 6-7 (3/7), 7-6 (11/9), 6-1
Cameron Norrie (GBR) bt Peter Gojowczyk (GER) 6-1, 2-0 -- retired
Karen Khachanov (RUS) bt Andreas Haider-Maurer (AUT) 7-6 (7/0), 6-3, 6-3
Guillermo Garca-Lpez (ESP) bt Stanislas Wawrinka (SUI x23) 6-2, 3-6, 4-6, 7-6 (7/5), 6-3
Dusan Lajovic (SRB) bt Jir Vesel (CZE) 6-3, 6-1, 6-3
Women
1st round
Katerina Siniakov (CZE) bt Victoria Azarenka (BLR) 7-5, 7-5
Madison Keys (USA x13) bt Sachia Vickery (USA) 6-3, 6-3
Caroline Dolehide (USA) bt Viktorija Golubic (SUI) 6-4, 6-4
Naomi Osaka (JPN x21) bt Sofia Kenin (USA) 6-2, 7-5
Mihaela Buzarnescu (ROM x31) bt Vania King (USA) 6-3, 6-3
Rebecca Peterson (SWE) bt Su-Wei Hsieh (TPE) 6-4, 6-3
Petra Kvitova (CZE x8) bt Vernica Cepede (PAR) 3-6, 6-1, 7-5
Lara Arruabarrena (ESP) bt Tmea Babos (HUN) 7-6 (7/5), 6-3
Mariana Duque (COL) bt Anastasija Sevastova (LAT x20) 4-6, 6-1, 6-3
Camila Giorgi (ITA) bt Grace Min (USA) 6-3, 6-2
Darya Kasatkina (RUS x14) bt Kaia Kanepi (EST) 6-4, 6-1
Maria Sakkari (GRE) bt Mandy Minella (LUX) 7-6 (7/5), 6-2
Carla Suarez Navarro (ESP x23) bt Ana Konjuh (CRO) 6-0, 6-1
Pauline Parmentier (FRA) bt Chloe Paquet (FRA) 3-6, 7-6 (7/4), 6-2