A former cycling champion has pleaded guilty to stabbing her former coach, who sexually abused her as a child.

Former Cycling Australia official, Warwick Phillips, was stabbed at his home at Kilburn in northern Adelaide in front of his wife and son in September last year.

The South Australian Supreme Court heard Phillips suffered severe injuries and was put in an induced coma in intensive care.

Phillips, 43, was given a suspended prison sentence in 2009 after pleading guilty to seven counts of unlawful sexual intercourse.

His now 20-year-old victim, who was 16 when Phillips abused her in 2008, has pleaded guilty to intentionally causing serious harm to Phillips and assaulting his wife.

Prosecutors have dropped an attempted murder charge.

During sentencing submissions, the court heard the woman was severely affected psychologically by the abuse and her promising athletic career had been ruined.

The court heard she stopped cycling after the abuse and became depressed and suicidal.

The young woman's lawyer, Grant Algie QC, said his client had a bright future before the offending, with real hopes of competing at Olympic level.

"It's fair to say that all of that changed, and changed dramatically for the worse, commencing in about April 2008 when her cycling coach, her newly-appointed cycling coach Mr Phillips commenced what was - to use a neutral term - a sexual relationship with [the girl]," he said.

Mr Algie said his client was overcome by emotion at the time she went to Phillips' house a year ago to try to talk to him and make sense of the offending.

But the young woman was called a liar by his wife and son and asked to leave.

"Subconsciously she may have stabbed her offender as she felt he had done to her in a symbolic way," Mr Algie told the court.

"It's entirely clear that the time of these offences she was suffering from significant and severe mental illness.

"The psychological effects she suffered are directly the product of the abuse perpetrated upon her by Mr Phillips, who is now juxtapositioned into the position of victim."

The woman read an apology to the court, saying she regretted her actions.

Mr Algie said his client was genuinely remorseful and making positive steps toward overcoming her severe psychological problems.

He urged the court to suspend any jail term, saying the woman already had spent more than four months in custody before being granted bail and was subjected to more brutality in prison.

"This really is an extraordinary case, a very sad one on many levels," the court heard.

"But in my submission the work that has been done to try to achieve rehabilitation and progress that has been made, the circumstances of this offending, her illness prevailing and contributing to the offending, the cause of that mental illness and her contrition - all of the above clearly give rise to the basis that there is good reason to suspend any sentence."

Prosecutor John Wells said the case was extraordinary but an immediate custodial penalty should be imposed.

"This is a relentlessly sad case of human wreckage," Mr Wells told the court

He said people must be deterred from revenge attacks and taking the law into their own hands.

"To take the law into one's own hands undermines the criminal justice system and should be strongly discouraged," he said.

"The Crown does not argue against the conclusion that [the woman] must be deserving of at least some level of sympathy, but the Crown does submit there remains the potential risk of reoffending and reoffending on the same terms."

The young woman will be sentenced next month.

The court also heard the woman had taken Cycling Australia to the Human Rights Commission over its handling of the offending.