The road to the 2020 Olympic Games Tokyo just got a lot more serious, with 84 U.S. National Team swimmers scheduled to compete at the Toyota U.S. Open, which begins tomorrow at the Georgia Tech Campus Recreation Center.

This meet marks the largest gathering of National Team athletes outside of Olympic and World Championship Trials, dating back to at least 2008.

Here are the top 5 five races to watch as the meet gets underway in Atlanta on Wednesday:

Women’s 800m Free

The very first event of the meet features a pair of 2016 Olympic gold medalists – Katie Ledecky and Leah Smith – along with several veteran and up-and-coming distance stars. Ledecky owns the world record at 8:04.79 and enters with an 8:10.70, while Smith is seeded at 8:16.33. Meanwhile, Ally McHugh, the 2019 NCAA champion in the 1650 free and 2019 national champion in the 800m free figures to be a threat, along with two-time open water Olympian Haley Anderson and newly-qualified open water Olympian Ashley Twichell.

Men 200m IM

The men’s 200m IM features an intriguing mix of veterans and newcomers who will likely be battling for the two Olympic roster spots in July. Chase Kalisz, the 2016 Olympic silver medalist in the 400m IM, enters the meet as the top seed, with world record-holder Ryan Lochte hot on his heels as the third seed. Lochte is on the comeback trail and aiming for a fifth Olympic team next June. Teenagers Carson Foster and Luca Urlando have made major improvements of late and will be shooting for top finishes, along with former collegiate standouts Will Licon and John Shebat.

Women’s 50m Free

The women’s 50 features a loaded field, led by 2019 world champion and American record-holder Simone Manuel. Manuel is seeded three-tenths ahead of anyone else at 24.05, just off her American record of 23.97. Meanwhile, Anna Hopkin and Erika Brown, who are tied atop the NCAA leaderboard in the 50 free this season with matching 21.19s in yards, are seeded second and fourth. Teenagers Gretchen Walsh (24.71) and Maxine Parker (24.75) are also in the top five. Keep an eye on veteran sprinters Margo Geer, Olivia Smoliga, Madison Kennedy and Mallory Comerford as well.

Men’s 100m Breast

With nine swimmers seeded under a minute in the men’s 100m breast, it figures to be an awesome race between a handful of Americans and international swimmers. American Andrew Wilson enters as the top seed, with Kazakhstan’s Dmitriy Balandin, the 2016 Olympic champ in the 200m breast, in second. Cody Miller, the 2016 Olympic bronze medalist in the 100m breast, and back-to-back NCAA champ Ian Finnerty sandwich Brazilian Joao Gomes for the next three spots. And, don’t count out American record-holder Kevin Cordes, who’s entered at 1:00.04.

Women’s 200m Free

The psych sheet for the women’s 200m free sounds more like an all-start lineup – Siobhan Haughey, Katie Ledecky, Simone Manuel, Taylor Ruck, Allison Schmitt, Leah Smith, Hali Flickinger, Mallory Comerford, Melanie Margalis – just to name a few. It will be a battle just to get into the top eight, with the final shaping up to be a great race between some very experienced and decorated swimmers.