PARIS—The loss of one set by a player is normally not the stuff of headlines at a Grand Slam tournament. That did constitute news at the French Open on Monday, because the player was No. 1-ranked Iga Swiatek and it had been more than a month since that happened to her.
The way it came about was noteworthy, too: She led the first set of her fourth-round match against 74th-ranked Zheng Qinwen of China 3–0, then 5–2, and was a point from claiming it on five occasions but could not seal the deal. Swiatek entered the day having won 20 sets in a row, and 48 of her preceding 49….