Coco Gauff remains on semi-final collision course with defending champion Aryna Sabalenka but she dropped her first set of the year at the Australian Open overnight. The world No.1 Sabalenka also refused to back a tennis legend's criticism of scheduling of women's matches.

Learner Tien pulled off a massive upset against Daniil Medvedev at the Australian Open. So, who is Tien, the 19-year-old out of California?

The Irvine native and 19-year-old qualifier, who played one semester at USC, wins a 4-hour, 49-minute thriller that ends at nearly 3 a.m. in Melbourne

U.S. 19-year old Learner Tien defeated No. 5 Daniil Medvedev in a fifth set tiebreaker in the Australian Open, making history in Melboune.

Learner Tien, 19, became the youngest American man to reach the Australian Open's third round since Pete Sampras in 1990.

Learner Tien has announced himself on the world stage with a huge upset victory over world No. 5 Daniil Medvedev, emerging as a new American tennis star