Resilient Pegula reaches WTA Charleston quarters with tiebreak win
A resilient Pegula, the world number five from the United States, eventually progressed just a day after laboring more than three hours to beat 72nd-ranked Yulia Putintseva of Kazakhstan.
The latest hard-fought win, clocking in at just over two hours, was revenge for Pegula, who was stunned by Cocciaretto at last year's Wimbledon in the round of 128.
Cocciaretto, ranked 43rd in the world, enjoyed an explosive start by dominating the first set.
Pegula's serve was notably wayward, with the American winning just 25 percent of first serve points.
"I don't know what I was doing out there... Oh my gosh, that's horrible," said Pegula after.
Pegula rallied in the second set, but was immediately broken in a topsy-turvy final set, in which she trailed 1-4.
The American hauled it back to 4-4, but then found the net on a break point that would have given her the lead.
Two points from defeat at 4-5, Pegula fought back to 5-5 and they advanced into a deciding tiebreak.
Pegula drew first blood, going up 1-0 off Cocciaretto's serve, then won every point on her own serve before Cocciaretto double-faulted to hand her the match.
"It was a challenge. She was playing really well," said Pegula.
"She beat me the last time we played, so there was a bit of a mental thing too, but I was able to serve really well, I think, at the end. And then I just held my nerve."
Pegula will play Russia's Diana Shnaider in the quarterfinals.
Pegula is chasing her second title of the year, after a victory in Dubai in February.