The win keeps his hopes of a 20th grand slam title alive.

The 19-year-old Tiafoe broke Federer in the first game of the match before capturing the opening set.

Federer continues his stunning  return from a six-month break after winning this year’s Australian Open and Wimbledon.

The Swiss ace got into gear after he broke Tiafoe to take a 3-1 lead in the second.

He then won nine of the next 10 games.