WUHAN, China — World No. 2 Caroline Wozniacki and Wimbledon champion Angelique Kerber were stunned at the Wuhan Open in China on Wednesday, both suffering shock defeats at the hands of less fancied opponents.

Olympic champion Monica Puig gave herself an early birthday present, beating Wozniacki 7-6 (12-10), 7-5 to reach the quarterfinals.

She was joined in the last eight by in-form Ashleigh Barty, who upset world number three Kerber 7-5, 6-1.

The 51st-ranked Puig was more than a match for Australian Open champion Wozniacki, who missed an opportunity to narrow the gap at the top after world No. 1 Simona Halep was knocked out Monday.

Wozniacki made a solid start to the match, winning the first three games, but the Puerto Rican Puig quickly fought her way back to win two grueling sets, the first of which was decided through a tie-breaker.

Puig, who turns 25 on Thursday, appeared unfazed by her opponent's stature, and kept the Dane under pressure throughout.

She will now face Wang Qiang of China, who ousted Australia's Daria Gavrilova 7-5, 6-2 to the delight of the home crowd.

Wozniacki failed to capitalize on the early exits of other heavyweights like Halep.

A successful run in Wuhan would have helped her move closer to qualification for the WTA Finals, which she won last year.

Six of eight places at the season finale in Singapore next month are still up for grabs — only Halep and Kerber have qualified so far.

Germany's Kerber was downed 7-5, 6-1 by Australia's Ashleigh Barty, last year's runner-up in Wuhan.