Olympic gold medallist Zac Stubblety-Cook has broken his silence on his decision to switch swim camps on the eve of the Commonwealth Games, revealing “cracks started to show” in his relationship with respected coach Mel Marshall during what he described as a “stressful” period.

Ahead of Australia’s swimming trials in Sydney, which run from Monday to Saturday, Stubblety-Cook has attempted to clear the air after being plagued by “disappointing rumours” since this masthead revealed he and Olympic girlfriend Ella Ramsay had abruptly left their Gold Coast training base in April following a dramatic falling out with Marshall and other swimmers.

Sources with knowledge of the situation, speaking on the condition of anonymity due to the sensitive nature of the issues, say the Griffith University Swim Club program, one of Swimming Australia’s high-performance hubs, has been an unhappy environment in recent months, with internal tensions simmering among swimmers and Stubblety-Cook and Ramsay at the centre of the turmoil.

Those sources indicate issues have been raised internally and finger-pointing has been rife, culminating in the pair relocating to Melbourne’s Nunawading Swimming Club, where they have been preparing for selection trials for the Commonwealth Games in Glasgow and the Pan Pacific Championships in California later this year.

Their departures followed those of Olympians Kaylee McKeown and Lani Pallister, who also left Griffith after Michael Bohl’s exit following the Paris Olympics.

Attempts to contact Marshall were unsuccessful, and Swimming Australia declined to comment on her behalf.

In an interview with this masthead, Stubblety-Cook said he had “tremendous respect” for Marshall’s career, which included guiding British breaststroke great Adam Peaty to multiple Olympic gold medals.

He was excited by the prospect of working with one of the world’s leading coaches, but admitted the relationship ultimately broke down.

“I think the cracks started to show, and it just didn’t really work out for us,” Stubblety-Cook said.

“There was a difference in opinion on a few elements of the program that we weren’t going to agree on … and that isn’t uncommon in the high-performance environment. It’s Mel’s program, and she has agency to run it how she sees fit.

“I’m in my third [Olympic] campaign now and wanted to move forward and get the best out of myself and I didn’t really see a way to do that.

“There was a meeting post nationals [in April] where there were a few options discussed. At the end of the day, it was pretty obvious from that discussion we were going to go our separate ways and move forward.

“I wish her and her squad all the best for the upcoming trials.”

Central to the story is Ramsay, an Olympic silver medallist in Paris as part of Australia’s women’s 4x100m medley relay team, who declined to comment through her management on the circumstances surrounding her departure.

“That’s probably for her to comment on. I don’t want to put words in her mouth,” Stubblety-Cook said. “There’s a number of situations that went on, but they’re not for me to speak to because it’s not my story to tell.

“Mel always treated us separately and as individuals.

“I’m 27 years old, and you’re going to butt heads with anyone in a workplace, but I would say that the allegations and rumours have been the most disappointing part because that’s not who I am and never how I’ve conducted myself. I was never made aware of those allegations or rumours.”

Stubblety-Cook said the timing of the move was not ideal, but he is confident it will not jeopardise his bid to defend his Commonwealth Games title in the 200m breaststroke.

“I definitely believed … I was giving it my best and never stepped a foot out of what I was asked to do, but it’s a difficult position being two years out of an Olympics. Athletes and coaches move all the time. It just happens to be in an awkward and precarious situation,” he said.

“Although it’s been a shit situation and a very stressful time, I’ve landed with a group that has embraced me. I cannot wait to get back racing and going hard. I’m a very empathetic person and not someone that likes to rock the boat.”

There could be an awkward encounter between the pair on pool deck at the Sydney Olympic Park Aquatic Centre, or later on tour if both Stubblety-Cook and Marshall are involved with the Dolphins.

“That’s a bridge I’ll have to cross when I get to it,” Stubblety-Cook said. “I think we can all remain professional. I think everyone has to respect Mel and what she’s done with Adam and the time she had in UK swimming.”

Asked about the fact that three Olympians – himself, McKeown and Pallister – had all left Griffith since Marshall arrived in early 2025, Stubblety-Cook was careful with his response.

“They’ve made it clear on why they left and have had success since they’ve left. That probably says enough,” he said. “I don’t think Kaylee was going to go slow wherever she swam.

“That’s Swimming Australia’s job to navigate all of that and comment on all of that. People can make their own deductions on what that looks like.

“There are two separate programs [at Griffith]. Mel Marshall operates in one program and Tom [Fraser-Holmes] operates as another program. It’s not for me to speak on how collaborative they work together or not.

“I’m very grateful for all of those people that have helped me along the way in this really hard time.”