Through much of the 1980s, Martina Navratilova was as unbeatable as anyone has ever been in the open era.
During a two-year stretch from December 1982 to December 1984 she had a match record of 167-2, and her 86-1 record in 1983 is the best single-season mark in open history. Her lone loss that year was not to Chris Evert or Tracy Austin or Andrea Jaeger or Hana Mandlikova or Pam Shriver, all of whom were stars at the time, but to a 17-year-old named Kathy Horvath.
Horvath was unseeded and ranked No. 45 when she pulled off one of the biggest upsets in a Grand Slam tournament, beating Navratilova 6-4, 0-6, 6-3 in the fourth round of the 1983 French Open.
Navratilova was 3-0 against Horvath without losing a set when they met at the 1983 French Open. But Horvath, who had a match point against Evert in a loss two weeks earlier on clay, was confident.
"It was one of those perfect days you can count on one hand," Horvath said years later in an ESPN.com story. "I woke up feeling great and when I started warming up I felt perfect, like I could put the ball on a dime."
Normally a baseliner, Horvath played an aggressive match against Navratilova, coming to net more frequently than usual.
Horvath won the first set, but when Navratilova blew through the second without the loss of a game, it seemed Horvath's upset bit had been thwarted.
However, Horvath hung with Navratilova in the third set, and Navratilova's coach, Renee Richards, and trainer, Nancy Lieberman, could be heard arguing in the players' box about strategy, according to the ESPN.com report.
Horvath finished off the stunning victory, but then lost in the next round to unseeded Mima Jausovec 6-1, 6-1.
Navratilova won her next 50 matches and went 128-1 over the next 19 months. Navratilova and Horvath met seven more times after Horvath's historic victory, and Horvath never won another set. At the age of 24, Horvath retired from professional tennis to go to college.