Serena targets Grand Slam No. 24

Serena Williams, riding an emotional roller coaster as she adapts to juggling tennis and motherhood, seeks to end 2018 on a high with a record-equalling 24th Grand Slam title at the US Open.

The US great counts six US Open victories among her 23 Slams and with one more would match Australian Margaret Court's record for most major singles titles.

She could also join Court, Evonne Goolagong and Kim Clijsters as the only mothers to win Grand Slam singles titles, but since an impressive run to the Wimbledon final -- where she fell to Angelique Kerber -- Serena has endured a lackluster buildup to the hardcourt showpiece in Flushing Meadows.

"I'm still at the very beginning, this is a long comeback," she defiantly told reporters after a second-round loss to Petra Kvitova -- winner of five titles this year -- in Cincinnati.

World no.1 Simona Halep arrives at Flushing Meadows buoyed not only by her first Grand Slam title at Roland Garros but by an impressive hard court campaign that included a victory in Montreal followed by a runner-up finish in Cincinnati.

The Romanian has reached six finals this year, displaying a new maturity on the court.

"Now she's understanding what the problems are, when she gets a little bit emotional how many points in a row she's losing because of that," Halep's coach Darren Cahill said.

Halep herself says that with her French Open victory, "Inside myself, something changed.

"I'm more relaxed. I feel thankful for everything I achieved. After French Open, I really started to believe that I'm a real No. 1."

World number two Caroline Wozniacki arrives in New York amid injury uncertainty, having withdrawn from Washington with a right leg injury and then retired with a left knee injury from her second-round match in Cincy .

Sloane Stephens, the world number three, will be in unfamiliar territory as she defends her first major title. A third final in the last five Grand Slams appears to be within her reach, but she too could face an early hurdle with former world number one Victoria Azarenka a possible third-round foe.

Kerber will be aiming to expunge the memory of a first-round exit last year.