The tennis world No. 6 faces a provisional suspension on March 12.
The American is one major behind the retired star.
Sharapova said she tested positive for meldonium and that she did not look at a banned substances list that the World Anti-Doping Agency had sent.
The Serbian world number one had a brilliant 2015.
Allegations of match-fixing have provoked an independent review of anti-corruption practices in tennis.
Betting on an Australian Open mixed doubles match was suspended on Sunday prior to the game.
The 17-time Grand Slam winner admits the prospect of his children playing tennis is not exciting.
The tennis world was rocked on Monday by allegations that the game's authorities have failed to deal with widespread match-fixing.
An investigation into corruption has alleged match-fixing by players in the world's top 50.
The world No. 2 faces a potentially tricky test against the German teen in the first round.
Britain's No 1 tennis player says he would leave the Australian Open to witness the birth of his first child.
It was the 10th career major for Djokovic but only his second U.S. Open.
The two men arguably are the greatest rivalry in tennis.
The two Italians faced off after upsetting the No. 1 and No. 2 seeds.
Two matches away from the mystical Grand Slam, the greatest tennis player alive falls to an unseeded opponent.
The tennis star was the No. 1 seed in the women's semifinals.
Serena Williams will face off against Roberta Vinci of Italy at 11 a.m. ET on Friday.
On Tuesday evening, Serena defeated Venus and Djokovic prevailed against Lopez to advance.
The quarterfinals begin without Andy Murray, who exited the tournament in an upset Monday.
As the tournament enters its second week, temperatures remain high and the stakes get higher.
A record number of players have already had to retire from the tournament.
A startling comeback and a calendar grand slam may be in the cards.
The Swiss tennis player is a transcendent moral force in a world of blood, sweat and brute effort according to his fans