Dayana Yastremska will miss the Australian Open after an appeal against a doping ban was rejected by the Court of Arbitration for Sport (Cas).

The 20-year-old took the case to Cas after the International Tennis Federation refused to lift the ban.

Her appeal was fast-tracked as she hoped to play in next week's Australian Open, but it was dismissed by Cas.

"Ms Yastremska therefore remains ineligible to compete, pending the final resolution of her case," the independent body added.

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 spent a 14-day period in quarantine with other players.

The Grand Slam event is set to start on Monday.