Storylines to watch at the Tokyo Olympics: Who will be the next Phelps, Bolt? Can anyone beat Biles?

Left to right: Caeleb Dressel, Eliud Kipchoge and Simone Biles. Getty Images

It's here! Well, almost. The Olympic Games -- the biggest sporting event on the planet -- are around the corner and it can all get quite overwhelming. There's so much happening, and so many champion athletes participating, but what makes for the most compelling storylines? Who are the Games' biggest superstars (or superstars-in-the-making)? We at ESPN recommend you keep an eye on these nine big storylines:

Who will be the next Phelps?

Think of the Olympics and you're probably automatically thinking...Michael Phelps. You can picture him now, can't you? Broad shoulders, broader smile, more gold medals on his neck than most countries have won in their entire history. Now retired, Phelps has left a bit of a power vacuum at the top of the swimming world. USA's Caeleb Dressel, though, has the potential to be the star who fills that void: For the past four years, he's been the best sprint swimmer in the world. He's won 15 medals (13 gold) over the last two World Championships (2017 and 2019) and in 2020, Dressel smashed the 50m butterfly, 100m butterfly and the 100m Individual Medley world records. He is likely to feature in seven races in Tokyo -- and he's favourite to win all of them.

Men's swimming events start July 24.

Can anyone be the next Bolt?

Usain Bolt's sheer force of personality made sprinting cool again and in simple marketing terms, he'll be an irreplaceable loss in Tokyo. And that's off the track. On it, no one came close to beating him in the 100m, the 200m and his Jamaican relay team in the 4x100m over the last three Olympics, and it's unlikely that anyone will win all three this time.

In the 100m, Trayvon Brommell won the US Olympic trials this year and is a strong contender along with compatriots Ronnie Baker and Fred Kerley (a close second and third in said trials). Canada's Andre de Grasse could be their biggest opponent. Noah Lyles, meanwhile, will be looking to stamp his authority in the 200m. He is favourite to win but watch out for his 17-year-old compatriot Erriyon Knighton, who broke Bolt's junior 200m record just last month and is the youngest US men's track Olympian since 1964.

Men's 100m semifinals and finals on August 1; men's 200m final on August 4.

Fraser-Pryce's hat-trick

Jamaica's Shelly-Ann Fraser-Pryce is looking to be the first woman to win the 100m sprint at three different Olympics (after 2008 and 2012). She may have finished third in 2016 but won the World Championships in 2019 and then ran the second fastest time in history earlier this year.

If she does win, at 34, she will become the oldest person to win an individual Olympic sprint. Her biggest rival, US trials winner Sha'Carri Richardson, is missing after being banned for marijuana use. Great Britain's Dina Asher Smith (the 200m favourite), the Ivory Coast's Marie-Josee Ta Lou and Jamaican Elaine Thompson-Herah are her prime opponents.

Women's 100m semifinals and final on July 31; women's 200m final on August 3.

Speaking of age...

Allyson Felix, track legend

Six Olympic Golds. Three Olympic Silvers. A 35-year-old mother of three. Shaming a sportswear giant into treating female athletes better. Still one of the favourites for the women's 400m. There's no one quite like Allyson Felix. Her rivals: Quenera Hayes, who beat Felix in the US trials, defending champion Shaune Miller-Uibo of the Bahamas and Jamaicans Stephanie Ann McPherson and Shericka Jackson. This could be one tight race.

Women's 400m final on August 6.

Simone Biles, the GOAT

Simone Biles does things that no one else has ever done. Literally -- there are now four original skills named after the US gymnast. Earlier this year, she became the first woman ever to land the Yurchenko double pike vault (a high-difficulty skill historically done only by men) in competition. There's Biles, a lot of fresh air, then everybody else. In Tokyo, the most decorated gymnast in history (with only 25 career World Championship golds) will be looking to retain her All-Around gymnastics crown from Tokyo -- no one has done that in 53 years -- and do a repeat of her four-gold winning performance from Rio.

Women's All-Around final on July 29.

Osaka and Djokovic go for glory

Naomi Osaka is already the face of women's tennis -- winning four Grand Slams in three years on court and becoming a champion for human rights and mental health off it -- and she could seal her superstardom with an Olympic gold on home turf.

Novak Djokovic, meanwhile, is coming off equalling Roger Federer's and Rafael Nadal's 20 Grand Slam titles and is the clear favourite (by a margin) for the men's singles gold. Having won the Australian Open, French Open and Wimbledon this year, gold in Tokyo and the title at the US Open could see him become just the second person ever to win a Golden Slam (after Steffi Graf).

Tennis starts July 24.

King Kipchoge looks to retain crown

Eliud Kipchoge is the only person ever to run a marathon in under two hours, even if unofficially. He is also the defending Olympic champion and is arguably the greatest marathoner of all time. While fellow Kenyans Lawrence Cherono and Amos Kipruto are in fine form, as are Ethiopians Leslie Desisa, Shura Kitata and Sisay Lemma, it will take something extra special to wrest the crown off Kipchoge.

Men's marathon on August 8.

Ledecky v Titmus in the pool

Katie Ledecky is a phenom -- she owns nine of the 10 fastest times in the 400m freestyle, the 23 fastest times in the 800m freestyle and the 10 fastest times in the 1500m freestyle (a new Olympic event). Tokyo may see an attempted coup: Australian Ariarne Titmus beat Ledecky in the 400m in the 2019 World Championships (Ledecky's first major loss over that distance in a decade) and nearly broke her record last month, swimming just 0.44 seconds off the pace. Ledecky v Titmus could be one of the showdowns of Tokyo 2020.

Women's swimming starts on July 24.

Gender history in the making

Laurel Hubbard may not win a medal in the women's 87kg weightlifting event, but when the New Zealand athlete steps onto the stage, she'll make history -- becoming the first transgender athlete to have ever competed at an Olympic Games. At 43, she'll also be the oldest lifter in the Games. Hubbard competed in men's competitions till 2013 but shifted once the IOC issued new guidelines allowing any transgender athlete to participate in women's competitions provided their testosterone levels are below 10 nanomoles per litre for at least 12 months before the Olympics.

Women's 87kg weightlifting on August 2.