Racing officials have interviewed Andrew Johns over the rugby league personality's involvement in events leading up to the acrimonious split between John Singleton and racehorse trainer Gai Waterhouse.

Johns met with a Racing NSW investigator on Friday, giving a statement ahead of Monday's inquiry into the performance of Singleton's outstanding racehorse More Joyous in the All Aged Stakes.

Johns' solicitor Colin Love and his manager John Fordham attended the meeting where he spoke to the Racing NSW official.

"... Andrew Johns met with Racing NSW's chief investigator Nathan Hayward this afternoon to provide a detailed statement in relation to the forthcoming inquiry into the running of the All Aged Stakes Randwick last Saturday," a statement from The Fordham Company said on Friday.

Singleton refused to divulge the names of "trusted friends" who had told him Waterhouse's son, the bookmaker Tom Waterhouse, was saying there was a problem with More Joyous.

But Johns denied Tom Waterhouse had tipped him off about the condition of More Joyous.

"As is the usual practice before matches, Tom and I engaged in some light-hearted discussions concerning rugby league and racing," Johns said in a statement earlier this week.

"I took the opportunity to quiz him about Saturday's big race meeting at Randwick, asked him what he liked and if there were any specials.

"Tom replied that he didn't like It's A Dundeel, More Joyous and All Too Hard.

Singleton publicly sacked Gai Waterhouse as the trainer of seven horses immediately after More Joyous ran second last in the All Aged Stakes.

His decision brought an end to a 35-year association with the trainer.

Singleton claimed he was prepared to put a $100,000 bet on More Joyous to win the All Aged before ex-jockey Allan Robinson told him there was a problem with the mare.

Robinson has emerged as a key figure in the saga but after appearing on national television and speaking on Sydney radio this week, his lawyer Chris Murphy said the retired rider was not well enough to attend Monday's inquiry.

Stewards will decide after reading Johns' statement whether he will be required to attend the inquiry to answer any questions.