Kyle Edmund's tough build-up towards the US Open continued as he was beaten by Portugal's Joao Sousa in the first round of the Western & Southern Open in Cincinnati on Monday.
The British number two recovered from a poor first set to level matters against the world number 54 but ultimately fell to a 6-3 2-6 6-3 defeat in just over one and a half hours.
It was a further disappointment for the 22-year-old, who was also beaten in his opening match by David Ferrer in the Canadian Masters in Montreal last week.
Edmund had made an encouraging start to his hard-court season, reaching the semi-finals in Atlanta and taking a set off Grigor Dimitrov at the Citi Open in Washington.
But Sousa proved too strong, breaking twice in the first set then again immediately at the start of the third which proved enough to consign Edmund to another defeat.