New Delhi, Sep 04 (ANI): Grigor Dimitrov slammed Roger Federer by 3-6, 6-4, 3-6, 6-4, 6-2 to reach his first US Open semi-final. He has become the lowest-ranked player to do so since 1991. Dimitrov, who had dropped all seven prior meetings with Federer, made a dramatic comeback to defeat the Swiss legend at Arthur Ashe Stadium and will face Russian fifth seed Medvedev in Friday's semis. Grigor Dimitrov reached his first US Open semi-final to match the deepest Slam runs of his career from Wimbledon in 2014 and the 2017 Australian Open. Grigor broke Federer twice on the way to a 4-0 lead in the final set and the 38-year-old Swiss star had no effective reply. Federer started the match tremendously but was not able to maintain his usual high level against Dimitrov. The climax came in the fourth set, Dimitrov fighting off five break points to win the set and level match at 2-2.