TORONTO — Canadian swimming star Penny Oleksiak is returning to her roots.

The four-time Olympic medallist is leaving coach Ben Titley and the Swimming Canada High Performance Centre to return to Bill O'Toole and the Toronto Swim Club.

"I'm excited to be returning to the Toronto Swim Club to continue my training and I look forward to future collaborations with coach Ben Titley as I prepare for Tokyo 2020," Oleksiak said in a statement.

The 17-year-old from Toronto trained with O'Toole as an age group swimmer, winning six medals at the 2015 world junior championships. She trained out of the High Performance Centre the past two years.

"I'm very excited to be working with Penny again," O’Toole said. "We have always had a great relationship and shared in many successes."

Oleksiak won four Olympic medals training at the High Performance Centre, including a bronze in the 4x100-metre freestyle relay.

"Penny is a great athlete and we achieved great things together," Titley said. "I wish her and her coach all the best. I look forward to working with them on national teams and know she can do great things in the future. My door will always remain open to supporting this young woman as she progresses."