Paradorn Srichaphan moved a step closer to his third successive Long Island Cup title when he battled past veteran South African Wayne Ferreira 7-6, 7-5 on Wednesday to reach the quarter-finals.
The fourth-seeded Thai is bidding to emulate former world number one Ivan Lendl by becoming only the second man to win the tournament three years in a row.
The 32-year-old Ferreira, set to retire at the end of the season, gave Paradorn's supporters a scare when he broke serve to lead 2-1 in the first set.
Paradorn retrieved the break quickly but Ferreira matched him from the baseline to force a tiebreak.
An early forehand error from the South African set the tone as Paradorn led 4-0 and, although Ferreira fought back to trail 4-3, the Thai took the tiebreak 7-3.
Instead of knocking the stuffing out of him, the loss of the first set seemed to inspire Ferreira.
Paradorn scrambled to save break points in two service games at the start of the second set but then missed four chances of his own to go ahead.
With a second tiebreak looking inevitable, Paradorn finally broke Ferreira in the 11th game before serving out for victory in the last warm-up event for next week's U.S. Open.
"I have played Wayne three times this year now and it's always tough," Paradorn told reporters. "Sometimes I tried to go for the lines too much and I made mistakes.
"He has to be the most experienced player on tour. He's been out there 12 or 13 years but still he's fresh and moving really well.
"But every time I step on the centre court here I feel like this is my place to do well. This is my third time here and I have won it twice so there's got to be a lot I like about it."
Paradorn will now enjoy a day off before his quarter-final against seventh seed Joachim Johansson of Sweden, who put out Austrian Stefan Koubek 6-2, 6-4 in the night match.
Earlier, Russian Dmitry Tursunov won a marathon battle with American Jan-Michael Gambill 6-7, 7-6, 7-6 in two hours 55 minutes.
It equalled the longest match recorded in the event's history, a first-round encounter in 1993 between Jan Siemerink of the Netherlands and Brazilian Luis Mattar.
Tursunov now meets 10th seed Jurgen Melzer after the Austrian beat another Russian, Igor Andreev, 6-3, 6-4.
Second seed Lleyton Hewitt of Australia, who won last week's Washington Classic, faces Frenchman Michael Llodra on Thursday for a place in the quarter-finals.