Shelton stuns Tiafoe to carry home hope of ending men’s US Open title wait

• 20-year-old faces Djokovic in last four after 6-2, 3-6, 7-6, 6-2 win
• Muchova thrashes Cirstea 6-0, 6-3 to reach semi-finals

Twenty years after Andy Roddick kicked down the door and battered his way to the US Open title, another howitzer-armed American tenderfoot who doesn't know what he doesn't know is two wins from matching the feat.

Ben Shelton, an unseeded 20-year-old from Atlanta who has burst from obscurity to become the surprise package of the tennis season, overcame Frances Tiafoe 6-2, 3-6, 7-6 (7), 6-2 in a tense US Open quarter-final on a muggy Tuesday night at Arthur Ashe Stadium to reach the last four at Flushing Meadows in only his fifth career appearance at a grand slam.