racket in the third set, which resulted in a match-ending penalty. At the Madrid Masters in the beginning of May, Dimitrov was unable to defend his quarterfinal from the previous year, suffering a first round exit in straight sets to Pablo Carreño, not having lost even a set to the Spaniard prior to that match. In the following week, Dimitrov's position in the ATP ranking deteriorated further to No.35, a three-year low. The Bulgarian was then beaten again by Alexander Zverev in first round of the Rome Masters. This was followed by another first round loss at the French Open to Viktor Troicki, this time in five sets. In June, Dimitrov's downfall continued, as he played on grass courts in Stuttgart and in London, losing once again in the first rounds to the wildcard Juan Martín del Potro in straight sets, and to the returning from injury Janko Tipsarević, respectively. Being unseeded at a Major for the first time since 2013, Dimitrov ended his losing streak at the 2016 Wimbledon, first beating qualifier Bjorn Fratangelo and then 16th seed Gilles Simon, before losing to Steve Johnson. Soon after that, Dimitrov revealed that prior to Wimbledon he had split with his coach Franco Davín. The Bulgarian hired Daniel Vallverdu as coach. In July, Dimitrov was seeded 12th in Washington Open and had a bye into the second round, but had another disappointment, as he lost in straight sets to No. 82, Daniel Evans. At Rogers Cup, Dimitrov survived another early elimination against Yūichi Sugita in the first round, coming back from a set down and facing 2–5 in the second set tiebreak. That was followed by an easy win against wildcard Denis Shapovalov and then Dimitrov beat Ivo Karlović in straight sets in the third round. The Bulgarian lost in three sets to third seed Nishikori in the quarterfinals. Paired with Wawrinka, he beat Lucas Pouille and Dominic Thiem in the doubles, before losing to Henri Kontinen and John Peers. Dimitrov participated in the 2016 Summer Olympics in the first half of August, but lost in the first round to ninth seed Marin Čilić. The Bulgarian then had a good run in Cincinnati, reaching his third career Masters semifinal. He subsequently beat in straight sets Gilles Simon in the first round and then came back from a set to down to eliminate 16th seed, Feliciano López. In the third round Dimitrov