SYDNEY: Poland’s Agnieszka Radwanska clinched a seventh straight victory to reach the semifinals of the Sydney International yesterday, as she builds toward next week’s Australian Open.

The world No. 4 and tournament top seed overcame Italian world number 16 Roberta Vinci, 6-4, 7-5 in just over an hour and a half to move into the last four.

Radwanska, coming off a victory in Auckland last week where she beat Yanina Wickmayer in the final, will now face 2011 winner Li Na of China.

Li took two hours and 19 minutes to down teenage American qualifier Madison Keys, 4-6, 7-6 (7/2), 6-2 in a night match.

“I was happy I could stay at the same level from the beginning of the match to the end, it was a pretty good challenge,” Li said.

“She has a big serve. It’s very good that I could have the match before the Australian Open to see how strong I am on the court.” In the bottom half of the women’s draw, Slovakian world No. 15 Dominika Cibulkova upset French Open finalist and tournament third seed Sara Errani of Italy, 6-2, 6-1.

Cibulkova, who eliminated 2011 Wimbledon champion Petra Kvitova in the opening round, will face German second seed Angelique Kerber in the other semi.

Kerber overcame former US and French Open champions Svetlana Kuznetsova 6-3, 7-5 in the last night match.

While the men’s tournament has been strewn with injury withdrawals ahead of next week’s year-opening Grand Slam, Radwanska said she was relishing her run of matches leading into the Australian Open.

“So far I feel good, and I’m very happy that I can play good matches, already seven in a row,” she said.

“I think this year it’s the first time I’ve played two tournaments before a Slam. I never did that before.

“So far it’s good, so I’m happy with my performance. I’m going to keep going.” Runner-up to Serena Williams at Wimbledon last year, Radwanska found it tough going in the wind against Vinci, whose backhand slice troubled the top seed.

“Today it felt like it was freezing compared to yesterday,” she said.

“I think it was perfect weather to play, around 25 degrees (Celsius), but for sure the wind was tough. I think I played quite good in the wind.” While the mercury topped 42 degrees Celsius (107.6 F) in Sydney on Tuesday, it was forecast to peak at just 25 degrees on Wednesday.

Cibulkova was on top of her game, converting five of her six break points and winning 75 percent of her first serves against Errani.

Withdrawals continue

Meanwhile, top seed John Isner was knocked out by compatriot Ryan Harrison but at least he got out on court on a day when injury withdrawals continued to ravage Australian Open warm-up tournaments.

World No. 5 David Ferrer remained on course for his fourth Auckland Open title, albeit after a tough 6-4, 2-6, 6-3 battle against Taiwan’s Lu Yen-hsun in his first outing of the year.

Sydney men’s second seed Gilles Simon pulled out before his last 16 match because of a neck injury, while Kei Nishikori and world number nine Janko Tipsarevic became the second and third players to quit the eight-man Kooyong Classic exhibition event.

All are expected to play at Melbourne Park next week.

World No. 13 Isner, however, was hampered by a bone bruise to his right leg in his 6-4, 6-4 defeat to qualifier Harrison and was left thinking about pulling out of the year’s first grand slam.

“It’s better. Definitely better than I thought, but it’s not 100 percent,” the American told reporters. “I don’t know. I’ve got a decision to make shortly.

Australian Bernard Tomic confirmed his return to form by riding his improved serve to a 7-6, 6-2 win over fifth seed Florian Mayer and setting up a quarterfinal against defending champion Jarkko Nieminen.

“He’s one player I don’t like playing,” Tomic said of German Mayer. “He’s a great player, he beats the top four when he’s playing well... I’m playing really good tennis.” Sydney fourth seed Fernando Verdasco was also a loser, 6-3, 6-3 to Denis Istomin, while sixth seed Radek Stepanek withdrew injured after four points of his match.

Simon’s withdrawal followed those of compatriots Jo-Wilfried Tsonga and Richard Gasquet, who pulled out because of a hamstring injury and for “personal reasons” respectively.

“The week before the slams, players don’t want to take any risks, which is normal but sad also for this one because Sydney is a very nice tournament and deserves to have a very nice draw,” 2011 Sydney champion Simon said.

“We just try the maximum to be ready... I mean, for me today, there is no point in me going out and losing 6-2, 6-2 playing 50 percent.” Former US Open champion Juan Martin Del Potro knows all about injury setbacks but the Argentine world number seven got his 2013 season underway at Kooyong with a 6-4, 3-6, 7-6 round robin win over Paul-Henri Mathieu.

Japan’s Nishikori, the world No. 18, was forced to pull out with a knee injury, while Tipsarevic, a winner in Chennai last week, was a set down to Marco Baghdatis when he retired with a wrist injury.

There was better news on the weather front in Sydney with temperatures of around 25 degrees Celsius at the Olympic Tennis Center.