March, Dimitrov was third seed at both the Indian Wells and Miami Masters, but faced early eliminations by Fernando Verdasco in the second round and by Jérémy Chardy in the third round, respectively. Dimitrov rebounded on the next tournament, the Monte-Carlo Masters, advancing to the semi-finals of the clay event after beating No. 10 David Goffin in the quarter-finals. Dimitrov ultimately lost to world No. 1 Rafael Nadal. That was followed by a quarter-final in Barcelona, where Dimitrov lost to Pablo Carreño Busta. After the match ending handshake, Dimitrov accused Carreño Busta of stopping the point in the second set tie-break, which led to an unforced error by the Bulgarian. Carreño Busta denied the accusations. In May, Dimitrov lost in the second rounds of the Madrid and Rome Masters to Milos Raonic and Kei Nishikori, respectively. Dimitrov then lost in straight sets to Fernando Verdasco in the third round of the French Open. Dimitrov had his worst grass-court season since 2010, having recorded early losses to Novak Djokovic at the Queen's Club tournament and to Stan Wawrinka at the Wimbledon Championships. The second of the defeats came in the first round of the Grand Slam event. Dimitrov next played in August at the Toronto Masters, where he reached the quarterfinals, losing to Kevin Anderson. Dimitrov then failed to defend his Masters title in Cincinnati after he was beaten in the third round by the eventual champion Novak Djokovic in a tight three-setter. As a result, Dimitrov's ranking dropped to world No. 8. That was followed by first round elimination at the 2018 US Open, with Dimitrov losing to Stan Wawrinka in straights. Dimitrov contributed to Team Europe for winning the second edition of the Laver Cup. However his struggles with form continued after early exits at the China Open and in Vienna, losing to unseeded Dušan Lajović and Mikhail Kukushkin, respectively. Dimitrov's season ended after the Paris Masters, where he lost to fifth seed, Marin Cilic in the third round. Dimitrov didn't qualify for the ATP Finals, where he was the defending champion. Former world No. 1, Andre Agassi, joined Dimitrov's team prior to the Paris Masters. 2019: Shoulder injury, US Open semifinal Dimitrov started his campaign in Brisbane where he defeated Yoshihito Nishioka and John Millman in straight sets before losing to eventual champion Kei Nishikori in the quarterfinals. In January, Dimitrov reached the last 16 of the 2019