The period between each Olympics always produces a lot of change, but with the global pandemic delaying the Tokyo Games by a full year, even more time has elapsed than usual.

Over the last five years, many of the stars from the Rio Olympics have continued their winning ways, but some of the biggest names have officially retired from competition and seen exciting new faces step up to take their places.

Who’s back for another Olympics? Who’s missing? And who are the new names to know heading into these Tokyo Games? Some of the biggest stories are covered below.

Simone Biles still dominant

After taking a year off following the Rio Olympics, Simone Biles returned to competition and continued her dominant ways. She won her fourth and fifth world all-around titles in 2018 and 2019, and she remains unbeaten in all-around competitions since 2013. During that time, Biles also unveiled two new skills that had never been done before in women’s gymnastics (videos below).

The 24-year-old will remain the favorite for multiple gold medals in Tokyo and could become the first woman to win back-to-back Olympic all-around titles in more than 50 years.

From Phelps to Dressel

There was no late change of heart from Michael Phelps this time around. The most decorated Olympian of all-time officially called it quits after the 2016 Games and hasn’t looked back.

But the future of U.S. men's swimming looks to be in good hands thanks to the emergence of Caeleb Dressel. After winning two gold medals in Rio as part of U.S. relay teams, the 24-year-old has become a dominant force with 13 combined gold medals at the 2017 and 2019 World Championships. During the last world championships, he also broke Phelps' long-standing record in the 100m butterfly (video below). Dressel will enter the Tokyo Olympics as the favorite in the 50m and 100m freestyle, as well as the 100m butterfly. He could also compete on all four relay teams, which would give him a chance at a truly prolific medal haul.

A challenger for Katie Ledecky?

After the last Olympics, Katie Ledecky spent two seasons competing for Stanford University before turning pro in 2018. She’s continued her run of dominance since the Rio Games, but a genuine rival may have emerged in the form of Australian swimmer Ariarne Titmus. At the 2019 World Championships, Titmus defeated Ledecky (video below) in the 400m freestyle, although Ledecky was sick at the time and off her usual pace.

At Australia Olympic Trials this year, Titmus further cemented her status as a contender by posting the No. 2 times ever in both the 200m and 400m. The matchup between Ledecky, 24, and Titmus, 20, is one that will provide a lot of intrigue in Tokyo.

"Swimone" keeps winning

Five years ago, Simone Manuel became the first Black woman to win an individual Olympic gold medal in swimming. She followed that up by winning eight more gold medals (five in 2017, three in 2019) at the world championship level.

Surprisingly though, Manuel did not qualify for the 100m freestyle, the event she won in Rio and is the two-time reigning world champion in. (She later revealed that she had been dealing with overtraining syndrome in the leadup to Olympic Trials). However Manuel did qualify for the 50m freestyle, an event in which she won the world title in 2019 (video below).

Replacing Usain Bolt

Usain Bolt, one of the most famous Olympians of all-time, is now retired after sweeping the 100m and 200m sprints at three consecutive Olympics. He’ll finish his Olympic career with eight gold medals total (including relays), and he still holds the world record for both distances.

With Bolt gone, the question becomes, who is ready to step up and fill the void as the fastest man in the world? One contender is American sprinter Noah Lyles, who became the 200m world champion in 2019 (video below). At age 21, Lyles posted faster times in both the 100m and 200m than Bolt did at the same age, so he’s on a very promising trajectory. Turning 24 just a few days before the Opening Ceremony, Lyles currently holds the world lead in the 200m and has established himself as one to watch in that event.

New partners in beach volleyball

After winning a bronze medal together in Rio, April Ross and Kerri Walsh Jennings parted ways and teamed up with new partners in a quest to add to their Olympic medal collections, but only one will be in Tokyo.

Ross and Walsh Jennings announced their split nine months after the Rio Games. Ross then reached out to Alix Klineman, an indoor volleyball player who had missed out on making the Olympic team several times, and mentioned she was looking for a new partner. Klineman made the transition to beach volleyball and ultimately teamed up with Ross after the end of the 2017 season. The "A-Team" won silver at the world championships in 2019 and is now one of the top-ranked teams in women's beach volleyball. As for Walsh Jennings, she partnered with 2016 Olympian Brooke Sweat but fell just short of qualifying for her sixth Olympic Games.

USWNT coming off World Cup run

The U.S. women’s soccer team saw their streak of three consecutive Olympic gold medals come to an end in Rio, but they bounced back in a big way by winning the Women’s World Cup in 2019. During that run, many of the USWNT players became big-time stars, including team captain Megan Rapinoe. They’ll attempt to become the first women’s team to take Olympic gold after winning the World Cup.

On the men’s side, the U.S. will be missing from the tournament for the third consecutive Olympics after the country’s Under-23 team lost the decisive match during an Olympic qualifying tournament. It continued the U.S. men’s recent struggles, as the senior team similarly failed to qualify for the 2018 World Cup. Thanks to a crop of young players breaking through for major European clubs, the arrow is pointing upward for U.S. men’s soccer in general, but USMNT fans will have to wait at least three more years to watch their team play at the Olympics.

NBA scheduling impacts U.S. basketball roster

American fans are used to watching some of the NBA’s biggest stars team up in a quest for Olympic gold every four years, but things weren't quite so straightforward this year. Like all other major sports leagues, the NBA schedule was upended by the global pandemic, so the past season featured a compressed schedule with a later end date. Game 7 of the NBA Finals could potentially be played on July 22, three days before Team USA’s opening game.

That left the roster for Tokyo in a state of uncertainty, as many of the big names were unable to make a decision about joining Team USA until later in the process. A 12-man roster was eventually named, but USA Basketball was given the flexibility to make replacements (which is something they ultimately needed to do). Despite the quick turnaround, three players involved in the NBA Finals — Devin Booker of the Suns, and Jrue Holiday and Khris Middleton of the Bucks — agreed to join the team in Tokyo.

Breakout tennis star Naomi Osaka set to make Olympic debut

Since announcing her arrival with a U.S. Open title in 2018, Naomi Osaka has become a bona fide superstar in the world of tennis. On the court she’s collected four Grand Slam titles, and off the court she’s become a prominent advocate for social justice issues. She’s now one of the highest-earning athletes in the world.

But the Olympics are uncharted territory for the 23-year-old. Osaka’s set to make her first appearance at the Tokyo Games, and she’ll get to do it representing the Olympic host nation, Japan.

New (and old) sports join the Olympic program

Six new sports were added to the Olympic program for the Tokyo Games – baseball, softball, skateboarding, surfing, sport climbing, and karate – while the basketball program expanded to include a new 3x3 tournament.

In the case of softball, American fans will see the return of a few familiar faces. The U.S. team will include pitchers Cat Osterman and Monica Abbott, both of whom were on the roster in 2008 when softball last appeared on the Olympic program. The U.S. lost to Japan in the gold medal game that year.

With skateboarding and surfing among the events making their Olympic debut, Olympic audiences will be introduced to established stars of those sports like Nyjah Huston (skateboarding) and Carissa Moore (surfing) for the first time.