Two-time defending champion Caroline Wozniacki overcame Urszula Radwanska of Poland 7-6 (4), 6-2 on Tuesday to reach the second round of the e-Boks Open.
The 21-year old Dane was down a break in the first set before rallying to force the tiebreaker. She then broke three times in the second to clinch the victory in 2 hours, 5 minutes.
The sixth-ranked Wozniacki will next play Pauline Parmentier of France, who ousted Anna Chakvetadze of Russia 7-5, 6-1 on the hard courts at the Farum Arena.
Fourth-seeded Monica Niculescu of Romania also advanced, beating Valeria Savinykh of Russia 6-2, 6-2, while No. 5 Kaia Kanepi of Estonia ousted Anastasia Rodionova of Australia 6-3, 6-4.
Second-seeded Angelique Kerber of Germany also advanced, beating Stephanie Foretz Gacon of France 4-6, 6-2, 7-5.
Alize Cornet of France had the easiest win of the day, routing Danish wild card Malou Ejdesgaard 6-0, 6-0.
Seventh-seeded Ksenia Pervak of Kazakhstan had to retire from her match against Australia's Johanna Konta when trailing 6-3, 1-0.
Sixth-seeded Mona Barthel of Germany ousted Sweden's Johanna Larsson 6-3, 6-4, while No. 8 Sofia Arvidsson of Sweden lost 7-5, 5-7, 6-1 to Austria's Patricia Mayr-Achleitner.
In other first-round matches, Petra Martic of Croatia beat Germany's Annika Beck 6-4, 6-4 and Anne Keothavong of Britain ousted Hungary's Melinda Czink 4-6, 6-2, 6-3.