Top-seeded Serena blamed the wind for a string of unforced errors in her first event after a four-month layoff as she was sent packing 6-4, 6-7 (7/3), 6-4 in a two-hour, 14-minute arm wrestle with world number 72 Madison Brengle.

Auckland: Serena Williams suffered a shock second-round defeat at the Auckland Classic on Wednesday following her sister Venus's earlier withdrawal with an arm injury.

Top-seeded Serena blamed the wind for a string of unforced errors in her first event after a four-month layoff as she was sent packing 6-4, 6-7 (7/3), 6-4 in a two-hour, 14-minute arm wrestle with world number 72 Madison Brengle.

"I'm trying to think of a word that's not obscene but that's pretty much how I played," Serena told reporters.

"I just couldn't get used to the wind. My opponent played in the exact same conditions so obviously she was used to it and her game was more suited to it but it was just really annoying me for whatever reason."

Second-seed Venus decided to quit after suffering a sore right arm during her struggle to a 7-6 (7/2), 6-2 first-round victory over 18-year-old New Zealander Jade Lewis playing in her first WTA tournament.

Serena, playing in her first tournament since losing in the semi-finals of the US Open in September, was looking for a bold showing in Auckland, both to prepare for the Australian Open and to celebrate her New Year engagement to Reddit co-founder Alexis Ohanian.

After blaming rust for her sluggish first-round win over Pauline Parmentier on Tuesday, she succumbed in abject fashion a day later with a double fault on match point at 4-5 in the third set in the blustery conditions.

"I didn't hit any returns in the vicinity of the court," lamented Serena. "I've never returned like that in my life -- a little frustrating especially since I worked so hard in the offseason.

"I can take solace from the fact conditions won't be like this in Melbourne."

Blown away

Brengle dropped her second service game but at 4-1 down reeled off five consecutive games to take the first set.

In the second set she saved five set points before losing the tie break to Williams and in the final set she held her nerve as games went with serve until Williams double faulted on match point.

"Probably my least favourite conditions I've ever played in," said Serena. "I really abhorred the conditions. It was way too much for me. This is almost not a great opportunity to assess your game.

"At this rate at least I can get out of these conditions and get to somewhere better, some warm weather."

Brengle goes through to meet seventh seed Jelena Ostapenko in the quarter-finals while Venus's withdrawal gifted Japanese teenager Naomi Osaka a berth in the final eight where she will play eighth-seed Croatian Ana Konjuh.

The 36-year-old Venus Williams had complained of "feeling old" after dropping her serve four times and serving eight double faults against Lewis who was half her age.

"The first match of the year is never perfect," she said after the match but before deciding to pull out... I'm just feeling old."