Grigor Dimitrov has marked his ATP Tour Finals debut with a thrilling three-set win over Dominic Thiem.
The first Bulgarian ever to qualify for the season-ending championship, Dimitrov upset the Austrian fourth seed 6-3 5-7 7-5 in the opening match from the Pete Sampras Group.
World No.1 Rafael Nadal plays Belgian seventh seed David Goffin in the night match on Monday at London’s O2 Arena.
