The Court of Arbitration for Sport has begun hearing an urgent appeal lodged by young tennis star Dayana Yastremska as she makes a last-ditch attempt to play in the Australian Open.

Yastremska, 20, was provisionally suspended earlier this month after testing positive to a banned substance in an out-of-competition sample.

The Ukraine world No.29 later sparked controversy when she was filmed on a Tennis Australia charter flight to Melbourne despite her provisional ban.

Her first application to the International Tennis Federation to remove the provisional suspension was rejected.

But on Wednesday sport’s highest court said it was hearing an urgent appeal so that a final decision could be made by February 3, before the Open starts on February 8.

“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,” CAS said in a statement in the early hours of Wednesday.

“The CAS arbitration has commenced and the parties have agreed to an expedited procedure.”