After withdrawing from the Kremlin Cup, Nick Kyrgios said he was heading home to prepare for the 2019 campaign.
Australian Nick Kyrgios was on the end of a surprise first-round loss to the American qualifier Bradley Klahn, the world number 104 winning 4-6, 6-4, 6-3.
Team World slashed Europe's overall lead to 7-5 heading into Sunday's third and final day of the 2018 Laver Cup.
Swedish official Mohamed Lahyani triggered controversy last month after coming down from his chair to give advice to Nick Kyrgios at the US Open.
Roger Federer gave yet another sneak peek of his greatness with a spectacular shot that not only left the crowd dumbfounded but also got a priceless reaction from Nick Kyrgios.
Roger Federer will be seeking a 13th appearance in the US Open quarter-finals when he plays Australian John Millman.
Roger Federer made it 18 wins in 18 second round US Open appearances by seeing off error-plagued Frenchman Benoit Paire 7-5, 6-4, 6-4.
Australia's 17th-ranked Nick Kyrgios withdrew from the ATP Washington Open on Wednesday because of a hip injury.
Milos Raonic cranked up the fastest serve of the tournament on Wednesday with a 147mph (236.5km/h) howitzer.
Andy Murray gave an encouraging display in his first competitive match in 11 months after finally recovering from the hip problem that required surgery in January
Roger Federer will play for the 98th title of his career on Sunday against Milos Raonic.
Seven-time major winner Venus Williams suffered back-to-back opening-round exits at the Slams for the first time in her 21-year career.
Dimitrov downed the 17th seeded Kyrgios 7-6 (7/3), 7-6 (7/4), 4-6, 7-6 (7/4) in 3 hour 26 minutes and will face Britain's Kyle Edmund in the quarter-finals.
The 22-year-old was slapped with a USD 3,000 penalty for unsportsmanlike conduct early in his 6-1 6-2 6-4 win over Brazilian Rogerio Dutra Silva in a night match on Hisense Arena on Monday.
The 6-4, 6-2 win was Nick Kyrgios' fourth title on the ATP tour and his first on home soil.
Novak Djokovic, who has been sidelined since July with a right elbow injury, is making his long-awaited return to the game at an exhibition tournament in Abu Dhabi from December 28-30
World number one Rafael Nadal won his sixth title of another remarkable year as he punished a disgruntled Nick Kyrgios at the China Open on Sunday.
World number two Roger Federer handed Team Europe the maiden Laver Cup title after beating Team World's Nick Kyrgios in a super tie-break thriller in Prague.