Fifth seed Coco Gauff won an all-American quarter final against Madison Keys to reach the last four stage of the Dubai Open here on Thursday.

Gauff reached the third semi-final at WTA 1000 level or above in her career, with a 6-2, 7-5 defeat of Keys.

She will face top seed Iga Swiatek in the semi-final on Friday.

Australian Open champion Aryna Sabalenka, however, lost in the quarter finals to Barbora Krejcikova 6-0, 6-7 (2- 7), 1-6.

Krejcikova will face third seed Jessica Pegula who got a walkover against Karolina Muchova.

On Wednesday, Gauff didn’t have to take the court to reach the quarter finals, as ninth seed Elena Rybakina of Kazakhstan withdrew because of a lower back ailment. Rybakina is the reigning Wimbledon champion.

Swiatek barely worked up a sweat, yet she advanced to the semi-finals. The top-seed Pole crushed 14th seed Liudmila Samsonova of Russia in 76 minutes in third-round action.

And then, without even having to walk onto the court, the reigning French Open champion received a walkover into the semi-finals when Karolina Pliskova was forced to withdraw from the tournament due to a viral illness.

Earlier, Swiatek had reached the quarter finals by beating Samsonova 6-1, 6-0. Swiatek, a three-time grand slam champion, has won her last five matches including the successful defense of her Qatar Open title last week.

Pliskova had completed a 7-5, 6-7 (6-8), 6-2 win over Ukraine’s Anhelina Kalinina in the third round before exiting the event.

Sabalenka had improved to 13-0 this year with a 2-6, 6-1, 6-1 victory over Jelena Ostapenko to reach the quarter finals on Wednesday. But on Thursday, Krejcikova proved too good for her.

Krejcikova had advanced to the quarter finals, defeating fellow Czech player Petra Kvitova 6-3, 6-2.

Sabalenka was one of the favourites here, collecting a title in Adelaide and winning her first grand slam crown at the Australian Open.

She got the better of the defending Dubai Open champion Ostapenko, sealing a 2-6, 6-1, 6-1 victory in one hour and 41 minutes.

“I mean, she played unbelievable tennis in the first set,” Sabalenka said.

“I wasn’t ready for that fast tennis. She was just getting everything, and everything was in. I don’t know, magically I turned around this match.”

Written with Reuters & AP/PTI inputs