Cardinal George Pell has taken his legal fight to overturn his child sex abuse convictions to the High Court of Australia.
An application seeking leave to appeal has been lodged, following the Victorian Court of Appeal's dismissal of Pell's appeal in August.
The 78 year-old former advisor to the Pope is currently serving a maximum six-year prison sentence for the sexual abuse of two former choirboys at St Patrick's Cathedral, while he was the archbishop of Melbourne.
Pell has to serve three years and eight months in jail before being eligible for parole.
If leave to appeal is granted it will be his final opportunity to challenge the convictions, but there is no guarantee the High Court will agree to hear the appeal.
Pell's legal team had 28 days to lodge leave to appeal in the High Court after the appeal judges dismissed his case on 21 August.
The Cardinal's legal team had been thoroughly examining the court's judgment after a 2-1 split decision was handed down by the three judges.
His lawyers had submitted that the offending could not have occurred in the time frame given, in a busy cathedral after solemn mass and given the then-archbishop was always accompanied.
It was the testimony of the surviving victim that became a sticking point between the Court of Appeal judges.
Chief Justice Anne Ferguson and Justice Chris Maxwell dismissed the appeal ground that the jury's verdict was "unreasonable", finding instead the complainant was a compelling witness who came across as truthful.
"The complainant was a very compelling witness, was clearly not a liar, was not a fantasist and was a witness of truth," Chief Justice Ferguson said.
However the third judge, Justice Mark Weinberg, said he was "quite unconvinced" by the victim's evidence, stating it "contained discrepancies, displayed inadequacies" and it was possible that some of what he said was concocted.
The judges unanimously dismissed two other grounds of appeal, which argued there were errors in the way the trial was run.