By Ian Ransom and Shrivathsa Sridhar MELBOURNE, Jan 23 (Reuters) - Aryna Sabalenka and Coco Gauff took a rocky path to the fourth round of the Australian Open on Friday but Carlos Alcaraz glided into the last 16 in his 100th Grand Slam match.

Novak Djokovic suggests the American male players may not have adapted to the game as well as European players over the last two decades and that could be one of the reasons for their Grand Slam drought.

Alexander Zverev hopes this is the week he can shed the title of best men’s tennis player never to win a Grand Slam.

College tennis players succeeding at Grand Slams used to be seen as a quirk. Now it is a feature of the tennis elite.

On Saturday, the Polish tennis star overcame Anna Kalinskaya 6-1 1-6 6-1 to reach the Australian Open round-of-16. There, the No. 2 seed will face Australian qualifier Maddison Inglis, who progressed into the last-16 following Naomi Osaka's withdrawal.

Novak Djokovic gets a walkover in the fourth round of the Australian Open and advances to quarterfinals for record 16th time

Two of the top American players are close friends, fierce rivals — and drivers of a campaign for change in tennis.