American Francis TFO reached the US Open semi-finals for the second time in three years after his opponent Gregor dmitrov retired due to a leg injury TFO was leading the Match 6 to3 6 to 75 6 to3 4 to1 when demitro decided to withdraw the Bulgarian struggled with a groin injury which had also hampered him earlier in the season at Wimbledon despite the unfortunate end to the match TFO prays the high level of play from both sides he now faces 12th seed Taylor fr in an All-American semi-final with both players aiming to end a 21-year drought for US men's tennis at major tournaments TFO dominated early breaking dimitrov serve with a backhand winner in the fifth game of the first set and clinching another break on the fourth set point when dimitrov netted a forehand dimitrov fought back in the second set winning a tie break after tfo's errors allowed him to level the match however dimitrov's injury became apparent in the third set and after receiving treatment he could no longer compete effectively TF the 20th seed now looks ahead to what could be the biggest match of his career as he prepares to face Fritz