Grigor Dimitrov's first career victory over Juan Martin del Potro put him into the quarter-finals of the Western & Southern Open in Cincinnati on Thursday.
Dimitrov had lost all five previous meetings with the Argentinian, but the seventh seed ended his hoodoo with a 6-3 7-5 win.
But 11th seed Pablo Carreno Busta was sent home by David Ferrer, losing 6-4 6-4 in an all-Spanish clash.
Wildcard Jared Donaldson is into the quarter-finals after seeing off Nikoloz Basilashvili 6-4 7-6 (7/4), while Yuichi Sugita rallied for a 6-7 (0/7) 6-3 6-3 win over Karen Khachanov.
Source: PA
