Given that a tennis match had never before lasted as long as the one between John Isner and Nicolas Mahut, it's a reasonable assumption to think that there might have been a few issues throughout the match. A few things about how tennis matches work should be known first, such as scoring.
Tennis scores might seem strange and illogical at first, but they're actually fairly easy to comprehend. According to Sporting News, three phases make up many professional tennis matches: game, set, and match. A singular game requires either opponent to score four points to win. Think of a set as basically a collection of those games, and winning a set usually means winning at least six or more games. And finally, in most tournaments, a match is usually made up of three sets but in Grand Slams men play the best of five sets while women still play the best of three.
The match between Isner and Mahut lasted five sets, stretching a total of 11 hours and 5 minutes. Due to the sheer length of the match, problems such as fading natural light, and even a malfunctioning electronic scoreboard in their fifth and final set, led to subsequent delays and halts (via Olympics).
