A father accused of cruelty to his daughters as he coached them to become Wimbledon stars admitted the fun appeared to be going out of the sport when his eldest child was aged just six.

John De’Viana said he began to see the “crossover line” between coach and father, and brought in a psychological development coach after doing “a lot of research” on children in tennis.

The father is accused of subjecting his daughters, Monaei and Nephe, to years of physical and emotional abuse in his effort to set them on the path to Wimbledon glory.

But giving evidence in his defence De’Viana, who walked to the witness box with a stick, said he had recognised potential issues early on and sought advice from the Lawn Tennis Association.

The dad-of-two, of Brancaster Road, Newbury Park, told the jury at Snaresbrook Crown Court that he had reported so-called pushy parents.

He was asked by Tara Adkin QC, defending: “Are you aware of the existence of some parents who would push young children beyond their ability and force them effectively to do sports?”

He said he was, adding: “I saw it and reported others.”

Explaining his concerns as Monaei, now 21, became better at the sport, he said: “It got to a point where I started to recognise the fun element of her own success was waning.

“I began to understand the crossover line between coach and father. I felt that Monaei and I weren’t enjoying all the fun things that we used to do.”

He added: “As a father and a coach there was a fine line and I was already struggling to stay on balance.”

The jury heard De’Viana did karate as a child, competing for Great Britain and becoming European champion aged 17.

He later took up tennis as he was “looking desperately to fill the gap” when he gave up karate.

He said he would have “quite happily” let Monaei move on to something else had she said she did not want to play tennis anymore.

The court heard how the girls were later described in various terms including “idiot”, in expletive-ridden statistics sheets showing their performance in matches.

A list of comments written on the sheets by De’Viana were read to the jury.

The 54-year-old, referring to Monaei wrote: “what a f***, gave up”, “It was f***ing appalling. Mons kept missing. F*** me” and when she was aged 13 he referred to her as a “f***ing idiot”.

Writing about Nephe, who is now aged 19, he wrote: “I just don’t understand you Nephe. Why you don’t listen and have to argue. You always play wrong.”

When she was aged 11, he wrote: “Nephe is like a f***ing dog being told what to do.”

Earlier De’Viana’s former partner rejected a suggestion she was lying about the allegations of cruelty in a bid to help her in a court battle concerning contact with their children.

Michelle Horne, giving evidence via video-link, described De’Viana as controlling, saying he made Monaei play with a bat and ball aged three.

De’Viana denied this, saying the small bat and sponge ball became her “go-to toy”.

De’Viana denies two counts of child cruelty.

The trial continues.