Simona Halep ought to be the world number one, heading into the US Open having already won multiple grand slam titles.

With the pregnant Serena Williams absent from the WTA Tour, Halep is the most naturally gifted active woman in the sport right now.

But she has yet to turn her talent into titles, having lost on both of her appearances in a grand slam final, while the number one ranking continues to elude her.

Three times this year, Halep has gone into a match knowing victory would crown her - and three times she has lost.

The latest of those defeats, a 6-1 6-0 thrashing by Garbine Muguruza in the Western and Southern Open final, was frankly embarrassing.

Muguruza hammered Halep in under an hour, the Romanian humiliated as her attempt to reach the top of the world rankings failed yet again.

Halep had not dropped a set in the whole tournament before facing Muguruza but she won only 12 points as she was destroyed in a first set that lasted just 23 minutes.

"Maybe I feel the pressure and I don't realise it," Halep said after her defeat, somewhat stating the obvious. "Maybe I just played bad. I don't know what to say.

"But it's still there. I still have a chance, so I will work for it, and maybe one day it will be there."

Halep sits just five ranking points behind the current world number one, Karolina Pliskova, who lost to Muguruza in the semi-finals in Cincinnati. There has not been a closer margin between the world's top two since 2009.

And the fact she cannot even refer to the number one ranking by name makes it clear there is a glaring mental issue with Halep, a brilliant clay-court player who has twice lost in the French Open final.

She was edged out in three sets by Maria Sharapova in 2014 and suffered defeat to unheralded youngster Jelena Ostapenko this year.

Halep was an overwhelming favourite to beat the unseeded Ostapenko in Paris and raced into a commanding position, taking the first set and establishing a 3-0 lead in the second.

She even had break points to go 4-0 up, which would surely have been an unassailable advantage.

Then Halep collapsed.

Ostapenko's bold attacking game started to click, the fearless Latvian suddenly finding the lines, and the Romanian's nerve deserted her. It was a loss that stung.

Yet there was a similar story at Wimbledon only a couple of weeks later. Halep faced home hope Johanna Konta in the quarter-finals and was two points away from a victory that would have sent her top of the world rankings.

Then she lost.

Halep complained a call from the crowd distracted her during Konta's match-winning rally. While she had a point, it stank of sour grapes and felt like she was making excuses.

Time is on Halep's side. She is only 25 and has plenty more years at the top. But there is a suspicion that the longer her wait for a grand slam title and top spot in the rankings goes on, the more damaging it will be to her fragile mental strength.

Halep will still be among the front-runners for the US Open title despite being handed a tough opening round clash with the returning Sharapova, and her fans will be hoping this time she can go all the way. 

But until she can find a solution to her lack of resolve, the grand slam titles and the world number one ranking Halep so craves will remain beyond her grasp.