By: MileSplit's Johanna Gretschel

The USATF Junior Nationals this weekend in Clovis, California, kick off an exciting summer of Team USA track and field action. The top two finishers in each event qualify for the IAAF World Junior Championships in Bydgoszcz, Poland from July 19 to July 24. Many top athletes are entered here and at the U.S. Olympic Team Trials to be held in Eugene, Oregon, in July. This weekend is an indicator of their fitness and could give spectators insight to who could contend for spots on the Team USA for the Olympic Games!

Sydney McLaughlin ran 54.46 in the 400m hurdles to set a new national high school record and American junior record at New Balance Nationals Outdoor.

Sprints/Hurdles

100m

Who:Candace Hill, Teahna Daniels, Katia Seymour

When: Friday, 5:05 p.m. PT [First Round]; Friday, 8:00 p.m. PT [Final]

Why: America's youngest track pro in Candace Hill will test herself against NCAA indoor 60m champion Teahna Daniels. Hill, who represents ASICS, set the national high school record of 10.98 last June but has run just 11.19 (+1.6) so far this year. Daniels won the NCAA indoor 60m title as a true freshman for the Longhorns and owns a season-best effort of 11.52 in the 100m. While Hill takes the prospects of World Junior seriously, this event is also a warm-up of sorts for the Olympic Trials next weekend. Seymour is the No. 1-ranked prep in the nation this year at 11.26 (+1.9); she was second at the adidas Dream 100 last weekend.

Watch Katia Seymour run U.S. No. 1 11.26 in the 100m:

100m Hurdles

Who: Tonea Marshall, Chanel Brissett, Tia Jones, Brandeé Johnson, Alexis Duncan, Jasmyne Graham, Anna Cockrell 

When: Saturday, 4:55 p.m. PT [First Round]; Saturday, 8:20 p.m. PT [Final]

Why: This star-studded field could produce a national record. Six athletes here rank on the prep top 10 all-time list: Chanel Brissett (No. 3 all-time, 13.01), Tonea Marshall (No. 5 all-time, 13.04), Brandeé Johnson (No. 6 all-time, 13.08), Tia Jones (No. 7 all-time, 13.14), Jasmyne Graham (T-No. 9 all-time, 13.17) and Anna Cockrell (T-No. 9 all-time, 13.17). Graham has run a season-best mark of 13.27 in her freshman year at USC. Brissett won New Balance Nationals Outdoor over Jones, Johnson, Marshall and Cockrell.

Watch the post-race interview with Chanel Brissett after winning New Balance Nationals:

200m

Who: Candace Hill, Taylor Bennett, Briana Guillory, Celera Barnes

When: Saturday, 6:35 p.m. PT [First Round]; Sunday, 7:22 p.m. PT [Final]

Why: World Youth champion Hill has run a slightly wind-aided 22.38 (+2.1) this year, though she set the world youth best mark of 22.43 into a -0.7 meters per second headwind last summer. We don't see the 17-year-old ASICS losing here, but her top competition will include Baylor freshman Bennett, who has run 22.71 (-1.0) and Iowa State frosh Guillory, whose top mark of 22.95 (+0.7) was good enough to win the Big 10 Conference title. Barnes, the California state champion and a UCLA commit, is the top prep entrant with a season-best wind-legal mark of 23.5. 

400m 

Who:Kaelin Roberts, Sammy Watson, Lynna Irby, Hannah Waller

When: Saturday, 5:20 p.m. PT [First Round]; Sunday, 6:45 p.m. PT [Final]

Why: Our bets are on high schoolers to take the top two spots here. New Balance Nationals champion Irby mostly has W's on her resume, although one runner-up finish is particularly noteworthy: the 2015 IAAF World Youth Championships, where she clocked her PR of 51.79. That's the fastest time in this field and she's undefeated this year. Watson, the World Youth champion for 800m, has not lost a 400m race since 2014, including this year's loaded Prefontaine Classic. Roberts and Waller went 1-2 at the CIF State Finals: U.S. No. 2, 52.28 to U.S. No. 7, 53.01, and Waller enjoyed a nice win at the Brooks PR Invitational last weekend while taking down NCAA record-holder Courtney Okolo's meet record in 53.18.

Watch Hannah Waller break Courtney Okolo's meet record at Brooks PR:

400m Hurdles

Who: Sydney McLaughlin, Anna Cockrell

When: Friday, 6:45 p.m. PT [First Round]; Saturday, 7:25 p.m. PT [Final]

Why: McLaughlin, the No. 4-ranked woman in the U.S. this year, is a potential addition to the U.S. Olympic Team at the Trials in two weeks. Here, the national high school record-holder at 54.46 should easily secure a berth to Poland. Cockrell ranks No. 5 on the all-time list with her new PR of 56.28.

Alexa Efraimson placed sixth in the 1500m finals at the 2014 IAAF World Junior Championships in Eugene, Oregon. The 19-year-old will compete for a spot in the 1500m again at these championships, two weeks before she races at the U.S. Olympic Trials.

Distance

800m

Who: Sammy Watson, Jazmine Fray, Ersula Farrow

When: Friday, 5:55 p.m. PT [First Round]; Saturday, 8:00 p.m. PT [Final]

Why: IAAF World Youth champion Watson is the headliner here. She's run 2:03.06 this year, barely off the 2:03.0 standard to enter the Olympic Trials. The junior from New York won Brooks PR last weekend in a relatively pedestrian 2:05 and she'll want to make this sure this one is fast as it's her last shot to go to Eugene. Helping push the pace should be Fray and Farrow, who have progressed into consistent 2:04 performers at Texas A&M and Clemson, respectively.

Watch Sammy Watson win the 800m at the Brooks PR Invitational:

1,500m

Who: Alexa Efraimson, Kate Murphy, Christina Aragon, Katie Rainsberger

When: Friday, 7:30 p.m. PT [First Round]; Sunday, 7:42 p.m. PT

Why: 19-year-old Nike pro Efraimson owns a PR of 4:03.39 and has run 4:06.38 this year, the No. 11 time in the U.S. She will race the 1500m at the Olympic Trials two weeks after this, where she'll see familiar faces in Murphy and Aragon. Haven't you heard? It's the year of the 1500m! Four high school girls have rewritten the U.S. all-time top 10 list this spring and all are entered here, minus Stanford commit Ella Donaghu, who is a late scratch. Murphy broke out with a 4:07.21 run to win the adidas Dream 1500m last weekend; only Mary Cain and Efraimson ran faster as preps. Aragon has run No. 4 all-time 4:09.27 while Rainsberger, a Ducks commit, ranks No. 6 all-time with her PR of 4:12.62. Rainsberger has declared for the Trials and this is her last shot to run under the 4:09.5 standard.

Watch Christina Aragon qualify for the Olympic Trials 1500m with an impressive kick:

3,000m

Who: Fiona O'Keeffe, Kate Murphy, Destiny Collins, Katie Rainsberger, Erin Dietz

When: Saturday, 9:00 p.m. PT [Final]

Why: Get ready for a heated rematch of the CIF State Finals 3K between O'Keeffe and Collins. Collins, a Texas recruit, won last year in9:53, while Stanford-bound O'Keeffe won this year in 10:08. O'Keeffe is coming off a tough loss at Brooks PR, where she led for most of the race is entered in both the 3K and 5K but said at Brooks PR she will likely choose just one race. Dietz of Harvard won the 2015 Pan-American Junior Athletics Championship 3K in 9:36. Two top entrants in the 1500m will double up in the 3K: Rainsberger, the NXN champion and a 4:12 1500m runner, who says she will likely choose just one event, and Murphy, who says she is considering doing both events but wants to make sure she books a ticket to Poland.

O'Keeffe talks about keeping the pace honest at Brooks PR:

5,000m

Who:Anna Rohrer, Fiona O'Keeffe, Amy Davis, Bella Burda

When: Friday, 9:00 p.m. PT [Final]

Why: Two-time Foot Locker champion Rohrer redshirted the outdoor season after a strong freshman campaign for the Fighting Irish that saw her place fourth in the 5K at the NCAA Indoor Championship and set a PR of 15:32.03. O'Keeffe, the California state 3200m champion, said she will choose between the 5K and 3K here. The Stanford commit has run 16:28.35 on the track. Davis of Wisconsin and Burda of Villanova have both run 16:25.

3,000m Steeplechase

Who:Devin Clark, Rylee Bowen, Alex Harris

When: Saturday, 8:45 p.m. PT [Final]

Why: Clark set and reset the American junior record in the steeplechase multiple times this spring as a freshman for Arkansas, culminating with a 9:49.25, fifth place at the NCAA Championships. Bowen represented Team USA at the IAAF World Youth Championships last summer, though she finished behind Harris at USATF Jr. Nationals. Harris, of DMR national record-setting North Rockland High School, New York, placed third at the Pan-American Junior Championships in 10:31.79 last summer.

Watch the interview with Devin Clark after breaking her own American junior record in the 3K steeplechase at NCAAs:

10,000m Racewalk

Who:Lauren Harris

When: Sunday, 8:30 a.m. PT [Final]

Why: Harris, a high school junior from Sachem East High, New York, set the national high school record for the one mile racewalk at New Balance Nationals Outdoor in 6:52.23.

Alyssa Wilson ranks No. 2 all-time in the girls shot put with a mark of 55-9.25.

Field Events

Pole Vault

Who:Rachel Baxter

When: Sunday, 5:30 p.m. PT [Final]

Why: World Youth Championships finalist Baxter is undefeated this year in the pole vault, including a sweep of the Texas Relays, Arcadia Invitational, Brooks Mt. SAC Relays and the CIF State Finals. The junior from Canyon Anaheim Hills High School ranks No. 4 all-time with her best of 14-3.

Long Jump

Who:Samiyah Samuels, Bria Matthews, Tara Davis, Margaux Jones, Taylor DeLoach, Rhesa Foster

When: Saturday, 3:45 p.m. PT [Final]

Why: Four 21-plus-foot long jumpers headline the field, including Davis, the 2015 IAAF World Youth champion, and Samuels, who ranks No. 7 all-time in the event with a mark of 21-3.25 that landed her the indoor national title. DeLoach, the New Balance Nationals Outdoor champion, and Foster, the California state champion, aren't quite at 21 feet yet, but they do look the best of the group right now, as they rank No. 1 and No. 2 in the nation this spring with marks of 20-10.5 and 20-7.5.

Samiyah Samuels reflects after jumping 21-3.5, the seventh best all-time mark:

Triple Jump

Who:Bria Matthews, Tara Davis, Chinne Okoronkwo, Asa Garcia

When: Sunday, 6:30 p.m. PT [Final]

Why: Matthews unleashed a 45-0.5 jump to win the ACC Championship title in May, making her the class of this field. Davis and Okoronkwo rank No. 1 and No. 2 in the nation this year with wind-legal marks of 43-2 and 42-2.25.

Tara Davis talks about winning the California state meet in the triple jump and taking second in the long jump:

Shot Put

Who:Alyssa Wilson, Nickolette Dunbar, Elena Bruckner

When: Sunday, 5:40 p.m. PT [Final]

Why: Three of the best preps of all-time face off here, led by Wilson--the No. 2 all-time performer as a high school junior with a best mark of 55-9.25. She recently won New Balance Nationals Outdoor ahead of Dunbar, who ranks No. 5 on the all-time list at 54-7.5. California state champion Brucker ranks No. 6 on the all-time list with her PR of 54-7 and is undefeated this season.

Discus Throw

Who:Elena Bruckner, Alyssa Wilson, Kiana Phelps

When: Friday, 7:15 p.m. PT [Final]

Why: Texas commit Bruckner has the best throw in the field by more than one full foot at 186-10, which ranks No. 4 all-time. She is looking for redemption after placing just second at the CIF State Finals. Could U.S. No. 2-ranked Wilson or U.S. No. 3-ranked Kiana Phelps, the New Balance Nationals Outdoor champion, sneak away with this one?