Sonny Bill Williams has had major heart surgery after doctors found a serious problem during a routine check-up

New Zealand rugby legend Sonny Bill Williams has undergone open-heart surgery after discovering he was born with a heart defect.

The 41-year-old former All Blacks star documented his health scare in a lengthy video on his YouTube channel, explaining that the condition was discovered during a routine check-up following neck surgery.

Speaking in footage filmed after the operation, Williams confirmed the procedure had been a success and said he was determined to use his experience to raise awareness of the importance of heart checks.

Williams revealed doctors had told him the previously undetected defect could have affected his sporting career, despite his exceptional fitness.

Following the surgery, he admitted recovery was tough.

“It’s the hardest thing I’ve ever done. Day two, honestly, I thought I wasn’t going to make it. It was crazy,” he said.

“I’m so grateful. The doctor I’ve seen this morning, he’s just told me that having this heart implication throughout my life would have implicated me and my sporting career. And upon reflecting, I feel like towards my late-20s, I definitely felt like I couldn’t get as fit as I used to…

“The doctors both said that it’s a miracle that you found it because it’s a case of a perfectly fit looking person dropping dead. Because my heart was 7.5 centimetres, it was about to pop as the doctors said."

News of Williams' major surgery has sparked an outpouring of well-wishes from fans around the globe and some of the biggest names in the sport. Wales legend Jamie Roberts said on Instagram: "Recover well, pal", while the likes Ardie Savea and Beauden Barrett sent messages of support.

Williams has now offered an encouraging update on his recovery, telling viewers from his hospital bed that he had emerged from the operation in better condition.

“I have a better heart than when I walked in here,” he said.

Williams enjoyed a remarkable career across both codes of rugby, first establishing himself as a superstar in rugby league before switching to union.

He went on to win two Rugby World Cups with New Zealand, helping the All Blacks lift the trophy in 2011 and 2015.

Williams retired from both codes in 2021 before turning his attention to professional boxing. His most recent heavyweight bout took place last year.