Ukraine's Dayana Yastremska has had an appeal against a doping ban fast-tracked in order for her case to be resolved before the Australian Open.
With the event starting on 8 February, the Court of Arbitration for Sport said it will make a decision by 3 February.
The world number 29 was provisionally banned earlier in January for failing an out-of-competition doping test.
On Saturday, the International Tennis Federation said it had rejected the 20-year-old's attempt to lift the ban.
"The Cas arbitration has commenced and the parties have agreed to an expedited procedure in order to enable a sole arbitrator to issue a final decision by 3 February," said Cas.
Yastremska has denied using performance-enhancing drugs after testing positive for mesterolone metabolite, an anabolic agent, in November.
The Ukrainian, who has been ranked as high as 21 in the world, said she was "shocked" by the positive test and suggested it was the result of a "contamination event".
Despite the provisional ban, she was allowed to travel to Melbourne for the Australian Open and has been in quarantine with other players.
"In her appeal to Cas, Ms Yastremska seeks to have the challenged decision set aside and her provisional suspension lifted in order to be able to participate in the 2021 Australian Open tennis tournament," added Cas.