Darren Cahill is one of the most respected coaches on the tennis circuit. He led Lleyton Hewitt to be the youngest number 1 in history.
He was Simona Halep's coach and the Romanian reached 1 and won Roland Garros 2018. Jannik Sinner is Cahill's second coach after Simone Vagnozzi. Cahill helped Hewitt win the Australian Open and is now working with Agassi and Halep, as well as Carlos Alcaraz and Marco Cecchinato.