Jan Choinski and Jack Draper were knocked out of the first round of the Cincinnati Open on Thursday as fellow Briton Cameron Norrie progressed.
Choinski bowed out after a hard-fought contest with Argentina’s Thiago Agustin Tirante, with all three sets going to a tie-break.
The match lasted nearly three hours before Tirante won 7-6 (11-9) 6-7 (7-9) 7-6 (7-4) against Choinski, the world number 77.
Draper led 5-2 in the second set against Martin Landaluce but the Spaniard won the next five games to clinch a 6-3 7-5 victory.
British number two Norrie was broken once as he lost a tight first set before recovering to beat Croatia’s Dino Prizmic 3-6 6-1 6-4.
The world number 37, who reached the semi-finals in Los Cabos two weeks ago, edged ahead at 4-3 in the third set before setting up a second-round clash with Wimbledon runner-up Alexander Zverev.
Draper was playing in his first match since breaking down in tears during his return from injury last week and he looked set to force a decider against 20-year-old Landaluce.
But the former world number four spurned six set points and finished with 47 unforced errors and 12 double faults against the world number 64.
Draper, 24, was playing just his second match since June having recently lost to Terence Atmane at the Canadian Open.
A persistent arm injury kept Draper sidelined and caused his world ranking to plummet from fourth to as low as 160th in a 12-month period.
Since injuring his shoulder at the US Open in August, Draper has struggled with bone bruising and pulled out of scheduled comebacks at Wimbledon and the Washington Open this summer.
While he did not appear to be injured against Landaluce, he tired during the second set and his confidence seemed gone once the Spaniard made it 5-5.
Draper has recently consulted biomechanics expert Carlos Cano in a bid to resolve his injury problems, with the 61-year-old Mexican having already helped Arthur Fery become British number one.
