Former world number one Caroline Wozniacki is now just two matches away from claiming a second title on the Asia swing of what she described as “the most difficult season of her career”, while reigning world number one Angelique Kerber was stunned in the quarter-finals of the Prudential Hong Kong Tennis Open on Friday. Wozniacki was forced to dig deep to secure her spot in the semi-finals overcoming the challenge of China’s Wang Qiang 6-3, 7-5 in an entertaining match, which brought out the battling qualities in the fiery Dane. The fifth seed needed just under 90 minutes to secure the win and set up a last four clash against defending champion Jelena Jankovic who came back from one set behind to defeat France’s Alize Cornet 3-6, 6-4, 6-2 in the late session. Wozniacki acknowledged that she had struggled this term after missing a large part of the campaign through injury. “It’s definitely been one of the most difficult years of my career,” said the 26-year-old. “I’ve been sidelined for so long and I definitely think that that’s been difficult mentally. But ever since I’ve got my body back on track, I’ve been playing well so that’s a positive.” Wozniacki, the current world number 22, won her first title of the season at the Pan Pacific Open in Tokyo last month. “Trophies are what I’m here for and I’d love to win the trophy - no doubt. There’s some strong competition left and I’m just going to see what happens.” Earlier, top seed Kerber was dumped out in straight sets by the impressive Australian Daria Gavrilova in the tournament’s biggest upset so far. A stunned Centre Court witnessed the German, who had been in scintillating form this week, be overawed in 74 minutes by world number 38 Gavrilova. It was the first time in six attempts that the Australian had beaten Kerber, but Kerber said afterwards she had not been at her best. “I didn’t play at my top form today,” said the 28-year-old. “I made a lot of double faults and errors, which I normally don’t, but my opponent played well and she deserved to win.” For 22-year-old Gavrilova,who is still looking for her first title on the WTA tour, the win was significant. “I’m really excited. I’ve played Angie [Kerber] six times and now I’ve finally won. It’s pretty exciting. “I was prepared for a battle but I think Angie has had a long season and I think she was really tired,” said the Australian. “I didn’t expect to win that easily but I was ready to finally turn it around and get a win against her.” The defeat for Kerber now means that American Serena Williams, who she usurped at the top of the world standings earlier this month, has the chance to reclaim the number one spot at the season-ending WTA Finals in Singapore, which begin on October 23rd. “I’ve played a lot of matches this year. I think right now I need a few days off to get ready [for Singapore]. I need a lot of treatment right now to get ready,” said Kerber, hinting at a problem with her shoulder. Gavrilova’s reward for defeating last year’s runner-up is a semi-final date with France’s Kristina Mladenovic, who came back from one set down to secure a narrow 3-6, 6-3, 7-6 (7-3) win over American Bethanie Mattek-Sands.