Top seed Agnieszka Radwanska has breezed into the second round of the ASB Classic tennis tournament with a straight-sets win over former champion Greta Arn.

Radwanska, the Polish world No.4, defeated her Hungarian opponent 6-2 6-2 in 75 minutes in Auckland on Tuesday.

Arn, the 2011 champion, had a reprieve into the main draw after losing her final qualifying match on Monday.

The withdrawal of Radwanska's original opponent, Frenchwoman Kristina Mladenovic, because of a wrist injury allowed Arn in as the "lucky loser".

But she was outclassed by Radwanska, who showed precision and variety of shot to move her around court.

Two breaks of serve gave Radwanska the opening set.

The pair traded breaks early in the second, before Radwanska broke again in a marathon game five, which ended with an Arn double fault.

Radwanska broke once more in game seven and then served out the match with an ace.

In the next round, she will meet unseeded Romanian Simona Halep, against whom she has a 2-0 record.

Earlier, the tournament lost a third seed with the retirement of Romanian Sorana Cirstea because of a viral illness.

Cirstea, the fifth seed, had dropped the first set to Britain's Heather Watson 6-3 when she retired.

An interested spectator was Judy Murray, the British Fed Cup captain and mother of men's world No.3 Andy Murray.

On day one, defending champion and fourth seed Zhang Jie of China and American seventh seed Christina McHale were both upset.

In other first-round matches on Tuesday, No.6 seed Yaroslava Shvedova of Kazakhstan beat Spain's Lara Arruabarrena-Vecino 6-3 6-2, while unseeded Swiss Romina Oprandi downed Thai qualifier Nudnida Luangnam 6-0 6-2.

AAP