First let’s look at Jose Capablanca, the world chess champion from 1921 (or 1920, depending on legalities) to 1927. His string of games without a loss (grandmasters often draw games with other grandmasters), from 1916 to 1924 (a 63-game streak without a loss) is astonishing. For his whole life, with only 34 losses (out of 571 games) in serious chess competition, his mastery of the game is legendary. Not until the year 2000 did another player win the world title without losing a game in the title match. And what other world chess champion obtained the title with fewer loses in serious competition? Probably none, for it normally takes hundreds of loses in tournaments and matches to refine the world-class skills of a world chess champion.
Now look at Bobby Fischer, who probably learned much from his study of the games of Capablanca. According to Wikipedia, “starting at age 14, he played in eight United States Championships, winning each by at least a point.” In the 1963-64 U.S. championship, he scored a perfect 11-0, astonishing everyone, even though one of his strongest American competitors (Samuel Reshevsky) was absent from that tournament. Even more astonishing was Fischer’s streak in the 1970 Interzonal competitions. In the first two matches, against two of the strongest players in the world, he won all twelve games (no loses or draws), unheard of before or since. He then met the former world champion, Tigran Petrosian. The first few games were a struggle, with one win and one loss. After three draws, Fischer won four straight, taking him to the world championship match. But those 13 wins in a row (without any draws), against three serious official candidates for the world championship match, were extraordinary. (And what other grandmaster has ever won four games in a row against Petrosian: probably none.)