Tennis: Birthday boy Tiafoe topples Dimitrov to reach quarters

Tennis - Australian Open - Fourth Round - Melbourne Park, Melbourne, Australia, January 20, 2019. Frances Tiafoe of the U.S. reacts after winning the match against Bulgaria's Grigor Dimitrov. REUTERS/Aly Song
Tennis - Australian Open - Fourth Round - Melbourne Park, Melbourne, Australia, January 20, 2019. Frances Tiafoe of the U.S. reacts after winning the match against Bulgaria's Grigor Dimitrov. REUTERS/Aly Song
Tennis - Australian Open - Fourth Round - Melbourne Park, Melbourne, Australia, January 20, 2019. Frances Tiafoe of the U.S. serves during the match against Bulgaria's Grigor Dimitrov. REUTERS/Aly Song
Tennis - Australian Open - Fourth Round - Melbourne Park, Melbourne, Australia, January 20, 2019. Frances Tiafoe of the U.S. serves during the match against Bulgaria's Grigor Dimitrov. REUTERS/Aly Song
Tennis - Australian Open - Fourth Round - Melbourne Park, Melbourne, Australia, January 20, 2019. Frances Tiafoe of the U.S. in action during the match against Bulgaria's Grigor Dimitrov. REUTERS/Edgar Su
Tennis - Australian Open - Fourth Round - Melbourne Park, Melbourne, Australia, January 20, 2019. Frances Tiafoe of the U.S. in action during the match against Bulgaria's Grigor Dimitrov. REUTERS/Edgar Su
Tennis - Australian Open - Fourth Round - Melbourne Park, Melbourne, Australia, January 20, 2019. Bulgaria's Grigor Dimitrov in action during the match against Frances Tiafoe of the U.S. REUTERS/Edgar Su
Tennis - Australian Open - Fourth Round - Melbourne Park, Melbourne, Australia, January 20, 2019. Bulgaria's Grigor Dimitrov in action during the match against Frances Tiafoe of the U.S. REUTERS/Edgar Su
Tennis - Australian Open - Fourth Round - Melbourne Park, Melbourne, Australia, January 20, 2019. Bulgaria's Grigor Dimitrov in action during the match against Frances Tiafoe of the U.S. REUTERS/Edgar Su
Tennis - Australian Open - Fourth Round - Melbourne Park, Melbourne, Australia, January 20, 2019. Bulgaria's Grigor Dimitrov in action during the match against Frances Tiafoe of the U.S. REUTERS/Edgar Su
Tennis - Australian Open - Fourth Round - Melbourne Park, Melbourne, Australia, January 20, 2019. Frances Tiafoe of the U.S. and Grigor Dimitrov greet each other after the match. REUTERS/Edgar Su
Tennis - Australian Open - Fourth Round - Melbourne Park, Melbourne, Australia, January 20, 2019. Frances Tiafoe of the U.S. and Grigor Dimitrov greet each other after the match. REUTERS/Edgar Su
Tennis - Australian Open - Fourth Round - Melbourne Park, Melbourne, Australia, January 20, 2019. Spectators react after Frances Tiafoe of the U.S. wins the match against Bulgaria's Grigor Dimitrov. REUTERS/Aly Song
Tennis - Australian Open - Fourth Round - Melbourne Park, Melbourne, Australia, January 20, 2019. Spectators react after Frances Tiafoe of the U.S. wins the match against Bulgaria's Grigor Dimitrov. REUTERS/Aly Song