Tiafoe staged a remarkable comeback from a set and 0-3 down on Wednesday against the Wimbledon finalist, to whom he lost three times last year, reports Efe.
"It means the world to me. I lost to Kevin three times last year (...) I went to a different place. I dug insanely deep," the 20-year-old said of his victory.
In the third round, Tiafoe is up against Italy's Andreas Seppi, who defeated Australia's Jordan Thompson in straight sets 6-3, 6-4, 6-4.