Second seed Ana Ivanovic has made it through to the second round of the ASB Classic tennis tournament on a day of upsets.

Three qualifiers have also progressed, while the respective fourth and sixth seeds – Romanian Sorana Cirstea and Czech Lucie Safarova, both exited at the first stage.

Ivanovic had to work for her 7-5 7-6 (7-2) win over American Alison Riske, saving five second-set points.

The Serbian, the world No.16, then closed out the contest with a flourish, winning the last six points of the tie-break.

Ivanovic twice got treatment on her right shoulder during the second set.

She then produced some big serving to get herself out of trouble at 3-5 and 0-40 down as Riske failed to convert four set points.

The former world No.1 and 2008 French Open champion saved another set point in the next game to level at 5-5.

Earlier on Tuesday, three qualifiers made it through to the second round.

The fourth – Estonian Anett Kontaveit – missed out only because she was beaten by another qualifier, Japan’s Sachie Ishizu, who won 6-3 1-6 6-3.

The day’s biggest upset belonged to Canadian Sharon Fichman, who downed Cirstea 6-1 6-4.

The result meant Cirstea has failed to make it past the first round in three visits to Auckland.

There was also a one-sided victory for Czech qualifier Kristyna Pliskova, who defeated Belgian Yanina Wickmayer – the 2010 champion and a two-time runner-up – 7-6 6-0 in just on an hour.

Safarova, meanwhile, went down to Japan’s Ayumi Morita 7-6 (7-2) 6-3.

Belgian third seed Kirsten Flipkens booked her place in the last 16 by beating Puerto Rico’s Monica Puig 6-4 7-5.