Few men have more experience than John Isner does at playing excruciatingly close matches.  The giant from Georgia loses serve so rarely and breaks serve so rarely that the margin between victory and defeat usually hinges on a handful of points.

This was the case again in Delray Beach on Thursday night, when the top-ranked American faced feisty Israeli Dudi Sela.  Isner enjoyed a 13-inch advantage over this opponent, and he had won their only previous meeting in relatively straightforward fashion.  For the second straight match, however, he started by struggling on serve.  Remarkably, Isner won barely half of his first-serve points in the first set, when he was broken twice.   The rust from an ankle injury incurred in January seemed to linger.

But Isner had mounted six comebacks from losing the first set since last August, including his first-round match against Michael Russell.  He turned the tide emphatically in the second set, dropping only four points on his serve and breaking Sela three times.  That momentum surge carried Isner to a 4-1 lead in the final set, when the match turned into a rollercoaster.

Two service holds from the finish line, the American could not close out the seventh game of the third set.  Sela fought his way back on serve to 3-4, only to face triple match point at 4-5, 0-40.  He erased all three of those match points and later a fourth to survive the multiple-deuce game.  Many an opponent would have despaired at so many wasted opportunities, but Isner merely held serve with conviction one last time.  So did Sela in his final service game, setting up a bizarre tiebreak.

After the two men traded mini-breaks on the first two points, Isner with a double fault, Sela earned what looked like a crucial mini-break a few points later.  The Israeli extended his lead to 5-2 in the tiebreak, thrusting the American’s back to the wall.  Suddenly, Isner won five straight points and the match.  The ebbs and flows of the tiebreak summed up the unpredictable, nerve-jangling match, which Isner must feel fortunate to have survived.  He has won 11 of his last 12 matches to reach a final set, including all five this year.

Joining the top-ranked American man in the Delray Beach quarterfinals are two of his compatriots, both of whom qualified for the main draw.  Steve Johnson upset top seed Tommy Haas on Wednesday and will face Feliciano Lopez during the day session, while Rhyne Williams weathered a three-set rollercoaster of his own against Marcos Baghdatis to set up an evening meeting with Isner.  Williams overcame the disappointment of failing to serve out the first set, which he eventually lost in a tiebreak, and grew progressively more dominant over the next two.

No matter the outcome, the fans of Delray Beach can count on seeing at least one man flying the Stars and Stripes in Saturday’s semifinals.