Swimming is nothing if not orderly, but get ready for a little chaos. Here comes the 4x100-meter mixed medley relay, making its Olympic debut in Tokyo on Saturday: two men and two women per country doing backstroke, breaststroke, butterfly, and freestyle, per the AP. The teams get to decide who swims each stroke, so a woman from one team and a man from the other could be doing the butterfly, say, at the same time. Coaches are looking for the fastest combination of swimmers in the four strokes. There are some general strategies that teams follow at the highest levels: Most put a woman on the final freestyle leg because the time difference between women and men is generally less on that stroke than the other three. Likewise, a man generally swims the breaststroke, where there's a larger gap between the fastest men's and women's times.
There's more wiggle room on the backstroke and butterfly legs. FINA, the sport's world governing body, added two mixed relays to its program at the 2015 world championships in Kazan, Russia, where the 4x100 mixed freestyle relay also debuted. "Different nations have different strengths on different legs and that brings in so many different strategies," Britain's Duncan Scott says. "You can be so far behind and claw it back." Swimmers negotiate very choppy water during the eight-lap race. A team that leads off with two men can build a big lead if others go with a different lineup. Things get so hectic, it's often hard to tell who's ahead. "You might be leading by a lot at 100, but then someone else might take over," UK swimmer Adam Peaty says. "And that's just the fun of it." (Read more 2020 Tokyo Olympic Games stories.)