American world number six Coco Gauff has ended her partnership with coach Brad Gilbert just two weeks after what she described as a “disappointing” US Open title defence.
Gauff, 20, won the first major of her career in New York last year under Gilbert’s guidance.
But she lost in the fourth round to fellow American Emma Navarro this year.
“Coco, at just 20 years young, your future is incredibly bright, and I wish you nothing but continued success ahead,” Gilbert, who also coached former Grand Slam champions Andre Agassi, Andy Murray and Andy Roddick, wrote on X.
“I’m excited for the next chapter in my coaching career.”
Gauff hired Gilbert to work alongside Spanish coach Pere Riba after a chastening first-round exit at Wimbledon last year.
That led to a turnaround in fortune as Gauff won 18 of her next 19 matches in her home hard-court swing, leading to title victories in Washington, Cincinnati and New York.
Beating Aryna Sabalenka in the US Open final was a career-best 12th victory in a row.
Riba left the team in November to leave Gilbert as the sole main coach.
This year, Gauff has not reached a final since defending the Auckland title in January.
After runs to the Australian Open and French Open semi-finals, she was beaten in the Wimbledon fourth round and reached the same stage at the US Open.
Fragility with her serve – having hit 19 double faults against Navarro – and forehand raised questions about whether she would continue with Gilbert.
“Thanks to Coco and the entire team for an absolutely amazing summer run in 2023 and for 14 months of incredible team effort,” added 63-year-old Gilbert.