Just Now! Urgent:Grigor Dimitrov Rushed to the Hospital in a Critical Condition Following Grigor Dimitrov's injury-related retirement during their quarterfinal match, Frances Tiafoe has advanced to his second US Open semifinal. In the fourth set, Tiafoe was leading 4-1 and won 6-3, 6-7, 6-3 when Dimitrov pulled out, giving the American the triumph. Tiafoe's victory maintains his aspirations of bringing an end to the 21-year absence of an American men's US Open champion. He has appeared to be playing well at home, defeating Alexei Popyrin to get here and surviving a five-set battle with Ben Shelton. With a head-to-head record of three victories from their four prior matches, Dimitrov, who has risen back into the top 10 of the world rankings, was a serious threat. But in the end, injury limited his challenge, advancing Tiafoe to the semifinals. Two years after his most successful home grand slam run, Tiafoe triumphed. As he attempts to become the first American man to win the US Open since Andy Roddick in 2003, he will now take on a fresh opponent in the semi-finals.