Former Scotland football captain Colin Hendry has admitted drink driving but is set to fight a ban from the wheel.
Hendry, 49, was arrested by police after being stopped while driving a blue Ford Focus in Church Road, Lytham, Lancashire at 1.15am on February 21.
He provided a reading of 63 micrograms per 100 millilitres of breath - the legal limit in England is 35 micrograms.
Blackpool Magistrates' Court was told that Hendry accepts the facts of the case but argues the amount of alcohol he consumed in a period of time did not "correlate" to the figure provided in the sample.
His solicitor, Gwyn Lewis, who specialises in defending motorist cases, said there were two possible explanations.
Either Hendry had some alcohol in his system that he was unaware of or he had a "quite rare" metabolism which meant a correct reading would not be given, he said.
Mr Lewis said: "We accept the prosecution case. The question is why is the sample reading what it is reading."
The court agreed to adjourn for a "special reasons" hearing in which Hendry will call evidence from a forensic service scientist and two civilian witnesses who were with him on the night of the incident.
Initial forensic tests conducted on behalf of Hendry had shown the figures did not correlate and further investigation was needed, said Mr Lewis.
The solicitor added that the later sentencing bench could have the option not to disqualify Hendry from driving but the conviction would stand regardless.
Hendry, of Coopers Row, Lytham, stood in the witness box and confirmed his address and date of birth before he pleaded guilty to the offence.
He was granted unconditional bail until April 22 when the case will be heard in full before sentencing.
Hendry had a long playing career, captaining his country in the 1998 World Cup and appearing for a series of clubs including Blackburn Rovers, Manchester City, Bolton Wanderers and Glasgow Rangers.