Career
Donaldson trained on the red clay in Argentina for two years instead of going the conventional route of a tennis academy or USTA Player Development. His time there dramatically improved his consistency, movement, and mental game. Having never claimed any prestigious junior crowns (Orange Bowl, Junior grandslams, Les Petits), Donaldson reached the final of the 2013 USTA Boys 18 National Championship at 16, where he lost to Collin Altamirano in straight sets, 6-4.
At the 2013 United States Open, he made the final round of qualifying, beating players ranking roughly in the top 200.
He continued to play extensively in the Turkey and United States Futures circuit until breaking through with three consecutive futures titles in June 2014. Donaldson qualified for his first Association of Tennis Professionals event at the 2014 Citi Open in District of Columbia. He made an official statement about turning pro instead of playing collegiate tennis on August 22, 2014, just short of his 18th birthday.
He received a maindraw wildcard into the singles and doubles tournament of the 2014 United States Open, and although he lost to Gaël Monfils in straight sets by a score of 4-6,2-6,4-6 he received high praise by many of the tennis elite. Singles: 1 (1–0)Editorial
Doubles: 1 (1–0)Editorial.