Nairo Quintana has launched an appeal to the Court of Arbitration for Sport against the decision to disqualify him from the 2022 Tour de France for a drug infringement.
Analysis of two blood samples from the 32-year-old showed the presence of banned drug tramadol.
The Colombian rider was stripped of his overall sixth-place finish and he later denied using the substance.
“The CAS arbitration has commenced,” the court said on Thursday.
“At this time, it is not possible to indicate when the final decision will be announced.”
A panel of arbitrators must be appointed before the date for a hearing can be set.
Following his disqualification from the Tour, Quintana said: “I am totally unaware of the use of this substance and I deny having used it in my career.”
The Arkea-Samsic rider is not competing in the ongoing Vuelta a Espana, an event he won in 2016, as he wanted to lodge an appeal to CAS. However, he confirmed he would return to the race calendar at the end of the season.
Using tramadol is an offence under International Cycling Union medical rules because of the side effects, which include dizziness, drowsiness and loss of attention.
Though banned since 2019, it does not constitute an anti-doping rule violation.
Quintana, who won the Giro d’Italia in 2014 and finished second in the Tour de France in 2013 and 2015, is still eligible to participate in the Tour de France as it was a first offence.