Third-seeded James Blake barely survived the third round, then booked a semi-final berth here on Thursday at the Pilot Pen Tennis US Open warm-up event.
On a busy day that saw three of the top four men's seeds tumble, Blake hung on by the skin of his teeth.
In his matinee third-round clash with Argentina's Agustin Calleri, last year's runner-up, Blake staged a remarkable comeback, saving three match points at 4-5 in the second set before prevailing 3-6, 7-6 (7/2), 6-1 in two hours before a partisan crowd.
Blake returned to court a few hours later to dismantle Spain's Fernando Verdasco 6-4, 6-2 in 60 minutes in the quarter-finals.
In women's action, Wimbledon finalist Marion Bartoli, the third seed, was humbled by sixth-seeded Russian Elena Dementieva 6-4, 6-2 in one hour and 39 minutes.
"Even though the score looks easy, it was not ... It could have gone either way," Dementieva said.
She now meets fellow Russian Svetlana Kuznetsova, who advanced without breaking a sweat.
Kuznetsova was up 6-2 when Italian Francesca Schiavone retired with a left ankle injury.