[4] Sumyk is married to former WTA player Meilen Tu, whom he coached to her highest career ranking of 35 in 2007.

In his third year of coaching Azarenka, the Belarusian won her first Grand Slam title at the 2012 Australian Open and reigned as the world number one for 51 of the 55 weeks that followed, during which she successfully defended her Australian Open title in 2013.

[2][7] Sumyk split from Azarenka shortly after the 2015 Australian Open after the Belarusian endured an injury-plagued 2014.

[13] According to an interview with the website Kommersant, she attributed a recent hip injury to Sumyk's training and tournament scheduling.

[14] She also discussed that any coaches have large egos[15] and that she realized at the Australian Open that the relationship with Sumyk was not conducive to making improvements on court.