Bradley Wiggins has received a 'strike' for the equivalent of a missed drugs test.
The Daily Mail reported Wiggins recorded a filing failure prior to the Rio Olympics where he won his fifth gold and British record eighth medal in all.
Athletes must give their whereabouts for one hour each day so they can be available for drug testing.
And Wiggins attributed the failure to confusion surrounding time differences on his return from May's Tour of California, the Daily Mail reported.
Wiggins' spokesman confirmed the missed test to Press Association Sport, but would not comment further.
Missed tests are not uncommon. Lizzie Deignan (nee Armitstead) successfully appealed to the Court of Arbitration for Sport against a ban for three missed tests within one year. Two are permitted in 12 months but a third triggers a suspension and possible two-year ban.
Deignan avoided the sanction after the first 'strike' was erased from her record.
Wiggins was among the athletes who were critical of Deignan.
The news comes as Wiggins faces scrutiny after seeking permission to use an otherwise banned substance before three major races, including the 2012 Tour de France when he became the first British winner.
Data stolen by hackers from files held by the World Anti-Doping Agency showed he received three therapeutic use exemptions (TUEs) for an otherwise banned drug.
The TUEs were for anti-inflammatory drug triamcinolone - a substance which has a history of abuse in cycling - on the eve of the 2011 and 2012 Tours de France and 2013 Giro d'Italia.
Wiggins and Team Sky principal Dave Brailsford, the British Cycling performance director until April 2014, have strenuously denied any wrongdoing, insisting each time the TUEs were medically necessary to deal with a pollen allergy that aggravates Wiggins' long-standing asthma condition.
The TUEs also had the approval of the UCI, cycling's world governing body, and there is no suggestion that Wiggins, who left Team Sky in April 2015, or the team, have broken any rules.
UK Anti-Doping is investigating allegations of "wrongdoing" in cycling and two of its investigators have visited the National Cycling Centre to meet with British Cycling staff.
The Daily Mail reported that UKAD was investigating Team Sky and Wiggins over the contents of a package allegedly delivered by British Cycling women's team manager Simon Cope to Team Sky at the conclusion of the Criterium du Dauphine stage race in France on June 12, 2011.
Wiggins has welcomed the UKAD investigation and believes he is not a subject.
Team Sky believe there has been no "wrongdoing" and say they are co-operating. British Cycling is also co-operating.
This week Wiggins angered the organisers of next week's Abu Dhabi Tour.
The organisers expected him to ride in the four-day race, but his focus is on the Six Day competitions in London and Ghent.
His eponymous team will compete in the race, which begins on October 20,
Wiggins plans to race on the track in the London Six Day, from October 25 to October 30, and the Ghent Six Day, from November 15 to 20, with Mark Cavendish. The pair are Madison world champions.
Wiggins, who last raced on the road at September's Tour of Britain, has announced his intention to retire at the end of 2016, but it is possible he could continue racing next year.
