The Italian announced through the Open that South Australian Cahill planned to retire at the end of 2025 with an unrivalled success rate with Sinner, the fourth player he has guided to become world No.1.
Sinner joined Lleyton Hewitt, Andre Agassi and Simona Halep as grand slam winners whom Cahill, the 59-year-old former US Open semi-finalist, has led to the very top of the game.
Joining as co-coach in 2022 alongside Italian Simone Vagnozzi, Cahill steered the 23-year-old to last year's Australian Open and US Open crowns, while he will start favourite for a third major in Sunday's title decider at Melbourne Park against German Alexander Zverev.
When revealing his coach's retirement plans, Sinner said it was a "huge honour" to be the last player Cahill oversaw full-time, and hoped to "make it a nice season".
But Cahill didn't want to take any spotlight from his Italian world-beater.
"Honestly, I don't want to make this in any way about me," Cahill said following his semi-final win over American Ben Shelton.
"We're concentrating on Jannik making the final, playing Zverev.
"This is not about me. This is about Jannik."
Jannik Sinner is flanked by Cahill (r) after winning the 2024 Australian Open title. (Joel Carrett/AAP PHOTOS)
Due to his coaching connections, Cahill has been able to pick the tennis brain of Agassi, who won four Australian Open titles among his grand slam haul of eight, and keeps a close eye on Sinner.
"We spoke to Andre today - he's a big fan of Jannik's, loves the way he plays," Cahill said.
"Always hearing words from him about what he sees from Jannik's game and where the improvements are coming from and where he still feels there could be more improvement in Jannik's game."
Cahill said he could see plenty of improvement in Jannik's game as he matured physically, growing five centimetres in the past two years.
He could also see the growth in his resilience, particularly in the way he dealt with the ongoing doping saga, with WADA appealing the decision not to ban the Italian ace after he twice tested positive for the banned steroid clostebol in March last year.
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"It's not easy to come back and defend a major for the first time in your career and he's had some stuff to deal with," said Cahill.
"We couldn't be prouder of the way that he's conducted himself, both on and off the court, the fight he's shown, the resilience.
"Nobody's bulletproof - I think we all have moments when it gets to you a little bit, but I think to a large extent he finds playing tennis matches to be his safe place.
"That's where he can go and do his thing and feel like this is what he knows, this is what he understands, what is what he's good at.
"It's become a home for him to step onto the court and play tennis.
"There's been a lot of pressure around him for the last nine months now but he deals with it as well as anybody that I've ever seen deal with pressure.
"He's an amazing young man that's been able to put that to one side.
"What will be will be. We don't know what's going to happen, but he can always hold his head up high and be proud of what he's been able to achieve."
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