Top seed Jelena Jankovic of Serbia and third-ranked Slovak Daniela Hantuchova enjoyed contrasting opening-round victories in the Auckland Classic on Tuesday.
World number 12 Jankovic encountered little difficulty in disposing of German Julia Schruff 6-3, 6-4, while Hantuchova was made to struggle all the way by 17-year-old compatriot Dominika Cibulkova before winning 6-1, 3-6, 6-2.
Hantuchova, ranked 17th in the world and a semi-finalist in Auckland last year, suffered a second-set stutter before booking her place in the last 16.
"The first set I played great, but after that I sort of relaxed a little bit too much and started to make too many mistakes," Hantuchova told reporters.
"In the third set, I started to focus again."
The home crowd had something to cheer about when 18-year-old Kiwi wildcard Marina Erakovic scored a career-best victory over the world number 90 and 2001
Her 6-3, 4-6, 7-5 victory was the first achieved over a player in the top 100 and will see her improve from her current place of 162 in the world rankings.
She now faces Greece's Eleni Daniilidou, the seventh seed and champion in 2003 and 2004.
"She's a very big girl, has big shots and a big serve and is very aggressive, so it may be a bit different from today," Erakovic said.
"I'll just have to think about my game and think about tactically what I should do and just focus on the tennis."
In other first-round matches, Martina Muller was the third seed to exit the tournament, the sixth-ranked German going down 3-6, 6-1, 6-1 to Argentina's Paola Suarez while American Laura Granville progressed 6-3, 6-4 at the expense of Italy's Romina Oprandi.