US Open: Serena Williams on course to pass Steffi Graf record after defeating Simona Halep to reach semi-final

Williams was given a scare in her 6-2, 4-6, 6-3 victory over Halep that continues her quest for a 23rd Grand Slam title

Serena Williams celebrates her quarter-final victory at the US Open (Getty)

Serena Williams kept her hopes of a record-breaking 23rd grand slam title alive by beating fifth seed Simona Halep at the US Open.

Williams was given the toughest fight of her tournament so far by Halep but survived in Arthur Ashe Stadium to win 6-2, 4-6, 6-3.

The American will now face 10th seed Karolina Pliskova in the semi-finals and stands two victories away from moving ahead of Steffi Graf's Open-era record 22 major triumphs.

Williams is also bidding to overtake Graf's record 186 consecutive weeks at world number one. She must do better than Angelique Kerber at Flushing Meadows to retain top spot.

The 34-year-old was pushed all the way by fifth seed Halep, who forced a decider after saving 12 break points during an enthralling second set.

"I knew I could play a lot better and I felt like I lost my rhythm in the second set," Williams said on court afterwards.

"And Simona started playing well and going for her shots. I knew if I wanted to win this I had to step it up in the third set."

Williams takes on the in-form Pliskova for a place in Saturday's final, with either Kerber or Caroline Wozniacki lying in wait.

Pliskova and Williams have delivered a combined total of 92 aces here - 60 for Williams, 32 for Pliskova - and power is likely to prove decisive again.

"I haven't played against many big servers recently, but she places her serve really well," Williams said.

"She definitely gets some speed on it, but her placement is really, really nice. Hopefully tomorrow I'll be able to read them and play OK."

Williams was taken to three sets for the first time at this year's US Open by Halep (Getty)

Pliskova knocked out Serena's older sister Venus in the last 16 and Serena admitted she would consult her sibling for advice on the Czech.

"I'm sure she will tell me something, but I'll be there," Williams said. "I'll be ready."

Pliskova will be playing her first grand slam semi-final after earlier easing past Croatia's Ana Konjuh 6-2 6-2.

The world number 11 had never gone past the third round of a major tournament before but arrived in New York on a high, having just beaten Kerber to claim the title in Cincinnati last month.

Williams celebrates her victory over Halep in the quarter-finals (Getty)

Her victory over 18-year-old Konjuh was her 10th in a row and took just 57 minutes.

"I'm not going to complain," Pliskova said. "I'm happy that it went so easy. Of course I was expecting a little bit tougher battle, but happy that it went so easy."

Pliskova lost her only previous meeting with Williams, at Stanford in 2014, and knows she will be the underdog again on Thursday.

"I'm sure always when you play someone who is better than you it's a little bit different because you don't have any pressure," Pliskova said.

"Like I had a little bit pressure against Konjuh that she was an outsider, so it's like you have to beat her.

"I just going to go and play everything that I have and put everything in that match because I have nothing to lose."

Pliskova also has a twin sister, Kristyna, who is ranked 122nd in the world. Asked what it would be like to have a twin on the tennis tour, Williams added: "It would be a living hell."

PA