Grigor Dimitrov came out strong but faded fast as the Winston-Salem Open's top seed was forced to retire from his match against Dominic Thiem, sending the Austrian into the Round of 16.
With less than a week to go before the start of the US Open, Dimitrov came out sharp, unleashing a torrent of backhanded slices to keep Thiem off balance as the Bulgarian raced through the surprisingly one-sided first set 6-0.
But things took a turn for the worse for Dimitrov at 2-2 in the second and he began to misfire in bunches in an apparent attempt to shorten points.
After a visit from medical staff, he stepped up to the line to serve while trailing 2-4 but decided he was feeling too unwell to continue and shook hands at the net, where he waited for Thiem while hunched over.