Serena Williams seeks the next step in her bid for a record 23rd Grand Slam singles title when she takes on Karolina Pliskova on Thursday in the US Open semi-finals.

Williams was undaunted by the relatively quick turnaround to the evening semis after battling to a three-set victory over resourceful Romanian Simona Halep on Wednesday night.

"The whole year you play every single day," Williams said, "so this is totally normal."

Williams has been speeding past Grand Slam milestones throughout the tournament.

Her win over Halep -- who saved a dozen break points in the second set -- stretched her record for Grand Slam match wins by any player, male or female, to 309.

She's gunning for an Open Era record seventh US Open title, which would also move her past the modern day record of 22 Slam titles she now shares with Steffi Graf and closer to Margaret Court's all-time mark of 24.

With world number two Angelique Kerber also through to the semis, Williams must at least make it to the final to extend her reign atop the world rankings to a record 187th week.

In Pliskova she'll face a long-time top 20 player enjoying a Grand Slam breakthrough many observers feel is overdue. The Czech has finally made it past the third round of a major at the 18th time of asking.

She came into the tournament with a WTA tour leading 407 aces in 2016 -- 147 more than the player with the next-most -- Williams with 260.

That serve and the easy power of her groundstrokes carried Pliskova to the biggest title of her career in August on the hardcourts of Cincinnati.

She upset Kerber in the final there -- thwarting the German in her first chance to seize the number one ranking -- but acknowledged that Williams will be another matter.

"Always there is a chance, so I'm going to do everything to get at least close to the final," Pliskova said.

Pliskova says she's a much different player than she was in falling in straight sets to Williams at Stanford two years ago, but whether she's improved enough to challenge Williams remains to be seen.

"She's a big hitter and she can have 50 winners and you cannot do much about it," said Pliskova, who ousted sixth-seeded Venus Williams in fourth round before dismantling Croatian teenager Ana Konjuh 6-2, 6-2 in the quarters.

Serena said she expected to get a few tips on Pliskova from her sister, but she didn't need Venus to tell her one thing: “There will be a lot of aces in that match".

- Kerber on fast track -

The other semi-final pits aspiring number one Kerber against former world number one Caroline Wozniacki.

Denmark's Wozniacki has years of success behind her to buoy her confidence despite her current world 74 ranking and unseeded status, in part a product the ankle injury that cost her three months of competition this year.

Twice the year-end number one, Wozniacki reached US Open finals in 2009 and 2014 and the semi-finals in 2010 and 2011.

"I always believe in myself no matter what my ranking," said Wozniacki after surging past a hobbled Anastasija Sevastova 6-0, 6-2 in the quarters. "I've beaten pretty much everyone in the draw before."

Kerber, in contrast, has been on the fast track in 2016, downing Williams to win her first Grand Slam title at the Australian Open and falling to the US star in the final at Wimbledon.

If Kerber can get past Wozniacki to her third Grand Slam final of the year Williams will have to beat her in the title match to stay atop the summit.

Kerber's newfound poise was on display in her quarter-final win over 2015 runner-up Roberta Vinci.

Three times Vinci went up a break in the first set and three times Kerber came back, finally gaining a decisive fourth break to take the set 7-5.

She produced just three unforced errors in winning the second set 6-0.

"I think I’ve grown a lot in the last few years," Kerber said. "I'm staying more positive and believing in my game. I think that right now I can win matches like that."

It's a change from her first Grand Slam semi-final appearance, at the US Open in 2011 when she fell to eventual champion Samantha Stosur.

"For me, I'm going out on Arthur Ashe, on the stadium, and playing against top player, I have more confidence going out there," she said. "I know that I can beat everybody."

Source: AFP