Cincinnati - Wimbledon champion Garbine Muguruza humbled second-ranked Simona Halep 6-1, 6-0 in Sunday's final of the WTA Cincinnati Open, denying the Romanian the world number one spot in the process.
Sixth-seeded Spaniard Muguruza needed only 56 minutes to capture her second title of the year and her first in a US event, taking the $522 450 top prize in the last major US Open tune-up.
"The American swing was never going my way," Muguruza said. "Finally, this year, I improved that."
It marked the third loss of the year for Halep when she was playing for the top ranking, also falling in the French Open final against Jelena Ostapenko and the Wimbledon quarter-final against Johanna Konta, each time after taking the first set.
"Maybe I feel the pressure and I don't realise it," Halep said. "Maybe I just played bad."
Halep's coach, Darren Cahill, told ESPN the French Open loss still haunts her, saying: "There's still a little leftover residue from Paris. It takes some time to get over that."
Halep apologised to spectators after the embarrassing defeat, thanking them for support "even if I played so bad and Muguruza played so well."
"It was a big shame to lose 6-1, 6-0 in the final," Halep said. "I got dominated. I can't control anymore the points. That's why I got down in my confidence."
Muguruza admitted after the lopsided win: "I feel a little bit bad. But I want to be in her position. I wanted to win. What can I do?"
Czech Karolina Pliskova, a semi-final loser to Muguruza, will remain world number one by a five-point margin over Halep.
"It's still there. I still have a chance," Halep said. "Maybe one day I will be there."
Serena Williams had been number one before her pregnancy break began earlier this year.
Muguruza, who jumps to third in Monday's rankings, becomes a favourite to capture a third career Grand Slam crown in Flushing Meadows after taking Wimbledon and last year's French Open.
"I'm happy people see me as a favourite but it not always happens that you win a tournament and then go ahead and win a Grand Slam," Muguruza said. "I'm happy to have the confidence. Beats not having it."
Muguruza, 25, broke Halep, 23, for a 2-0 lead and Halep double faulted away another break in the sixth game before Muguruza held to claim the first set in 23 minutes, aided by 15 Halep unforced errors.
"She was hitting pretty strong and started dominating me from the first point," Halep said. "After a few games I started to go down in confidence. I think she was just too good today."
In a 12-minute fourth game in set two, Halep netted a forehand and sent a backhand wide to squander her only break chances. Muguruza broke again in the fifth game and held serve to seize the crown.
"I was looking to be aggressive from the first moment," Muguruza said. "I felt very comfortable. My level was very high. Especially in the second set I felt I could raise it a little bit more and close the match."
Halep must now set aside the humiliation to focus on the US Open.
"I know I have to forget it. I have a much bigger tournament coming up," Halep said. "I don't want to go down too much. I don't want to analyse too much. It was a bad moment on court but it's just today.
"I'll go to New York and I'll build the confidence up. These moments are bringing you a lesson and I'll just learn from it."
Results on Sunday from the WTA and ATP Cincinnati Masters tournament (x denotes seeding):
Grigor Dimitrov (BUL x7) bt Nick Kyrgios (AUS) 6-3, 7-5
Garbine Muguruza (ESP x4) bt Simona Halep (ROM x2) 6-1, 6-0