Venus crashes out in Auckland as Wozniacki progresses
Venus Williams' title defence came unstuck at the first hurdle, while Caroline Wozniacki eased through to the second round.
Defending champion Venus Williams was a shock first-round casualty at the WTA ASB Classic, ousted 6-7 (4-7) 6-3 6-3 by Russian teenager Daria Kasatkina in Auckland on Tuesday.
Much had been expected of top seed and seven-time grand slam champion Williams, who boasted a 9-1 win-loss record at the tournament after taking out last year's final.
But Williams and her bid for back-to-back titles came unstuck in an error-riddled performance against unheralded 18-year-old Kasatkina - ranked 75th in the world.
Williams won a first-set tie-break, however, it was all downhill from that point as Kasatkina regrouped to triumph in two hours and 17 minutes at the International series event.
"She is an amazing tennis player and I respect her so much," said Kasatkina, who will meet Nao Hibino for a place in the quarter-finals. "It was an unbelievable match for me."
However, third seed and former world number one Caroline Wozniacki managed to win through to the second round after seeing off Danka Kovinic 6-4 6-4.
Wozniacki, who lost to Williams in last year's decider, was forced to dig deep against the combative Kovinic, having trailed 4-0 before winning six consecutive games to claim the first set.
The two-time US Open runner-up and Kovinic exchanged breaks late in the second stanza before the former eventually closed out the match.
Next up for Wozniacki is Christina McHale, who defeated Misaki Doi 6-2 6-4.
Fellow seed Barbora Strycova advanced courtesy of a 6-2 6-4 win over Kiki Bertens, former French Open champion Francesco Schiavone bowed out of the tournament, beaten 7-6 (7-3) 4-6 6-3 by Austrian qualifier Tamira Paszek, qualifier Kirsten Flipkens edged Bethanie Mattek-Sands 3-6 6-4 6-3, while Lucie Hradecka fell 6-0 6-3 to Julia Goerges.