The Diamond League returns on Thursday, July 6, in Lausanne, Switzerland. Wayde Van Niekerk is running his first serious 400 of the year, Genzebe Dibaba is entered in the mile, and Matt Centrowitz is entered in the 1500 meters. We preview the seven biggest races in chronological order below; all times Eastern.

Women's 400m Hurdles
​Who: Dalilah Muhammad, Shamier Little, Sara Petersen, Ashley Spencer, Zuzana Hejnova, Ristananna Tracey
When: 2:04 PM
Why: ​Muhammad, Petersen, Spencer, Hejnova, and Tracey were the top five finishers in the Olympic final, and Little just ran faster than all of them (except for Muhammad) in an outrageous U.S. final. In Sacramento, Muhammad and Little went 1-2 in 52.64 and 52.75 seconds, making them the fifth and ninth fastest performers of all time. That U.S. championship may have been the greatest 400 meter hurdles race of all time. Muhammad and Little will try to come back from the emotional high, while Spencer will try to rebound from barely missing the U.S. team.

Last year, i ran 54.02 and made an Olympic team

Today I ran 53.11 and got 4th.

Only in the USA

— Ashley Spencer, (@theTrackQueen) June 26, 2017

Best marks-for-place for 3rd, 4th, 5th and 6th.

This is the greatest women's 400m hurdles race in history.

— Jon Mulkeen (@Statman_Jon) June 25, 2017

Men's 1500m
Who: Matt Centrowitz, Elijah Manangoi, Ayanleh Souleiman, Silas Kiplagat, Andy Bayer, Filip Ingebrigtsen, Aman Wote, Bethwell Birgen
When: 2:13 PM
Why: Centrowitz has an Olympic gold medal, a world indoor championship, and silver and bronze world outdoor medals, but zero Diamond League wins. The nature of DL races is completely different than championship finals; it's almost a different sport entirely. But he has a reasonable shot of taking down the field here. The only Kenyan who finished in the top three at their trials entered here is Elijah Manangoi, and the only American entered is Centro's best friend Andy Bayer.

Manangoi is clearly the favorite here. He's only lost to three men this outdoor season--Ronald Kwemoi, Timothy Cheruiyot, and Jake Wightman. And none of them are entered here. However, Wightman's upset win at Oslo shows that Manangoi isn't invulnerable in a field like this.



If it's not Centro or Manangoi, who will it be? Olympic fourth-placer Ayanleh Souleiman has been nowhere near his 1:42/3:29 form this year, running 3:38 and 3:40 in 10th and 11th place finishes in Doha and Oslo and dropping out of the mile at Pre. Silas Kiplagat, the fifth fastest 1500 runner of all time, hasn't been much better this year--after running 3:32 for second at Doha, he's been 12th at Pre, seventh in Oslo, and 12th in the Kenyan trials.

Aman Wote of Ethiopia has raced more sparingly than the Kenyans entered, but the arc of his season is pointing the right way. At Doha, Hengelo, and Stockholm, he's steadily lowered his season best from 3:34 to 3:33 to 3:31. The two men who beat him in Stockholm, Timothy Cheruiyot and Sadik Mikhou, are not entered here. 

Women's Mile
​Who:​ Genzebe Dibaba
When: 2:33 PM
Why: This race might be a world record attempt for Dibaba, who owns two of the three fastest women's miles ever but not the world record. The WR is 4:12.56; Dibaba has run 4:13.31 and 4:14.30. She hasn't raced a 1500 or mile this outdoor season, so it's a little unclear where her fitness is. She's run 1:59 and 14:25, which at a minimum means she isn't ​out ​of shape. But who knows beyond that.

Men's 100m
​Who:​ Justin Gatlin
When: 3:20 PM
Why: Gatlin's win over Christian Coleman at the U.S. championships was one of the most stunning track results of all of 2017. The field Gatlin is facing here is not significantly better than the one he took down in Sacramento. Olympic fifth and sixth placers Akani Simbine and Ben Youssef Meite are probably his top two challengers here, along with U.S. third-placer Christopher Belcher.



Women's 800m
​Who:​ Sifan Hassan, Francine Niyonsaba, Laura Muir, Lynsey Sharp, Eunice Sum
When: 3:30 PM
Why: Without Caster Semenya or Margaret Wambui entered here, Niyonsaba is a lock to win. The more intriguing entries are Hassan and Muir--two of the best 1500 runners in the world making their season debuts in the event. New Oregon Project member Hassan might be the best 1500 runner in the world this year, while Muir won the Diamond League last year.  Hassan holds Dutch national records in the 1000m, 1500m, mile, 3000m, and 5000m, but at 1:55.54, the 800m might be out of reach.

Men's 400m
​Who:​ Wayde Van Niekerk
When: 3:40 PM​
Why: This is the Van Niekerk show. The 400 world record holder has spent the first half of 2017 racing heavily at shorter distances, running 100s and 200s all spring. He gave the world a taste of what he was capable of in a longer sprint last week, running 300 meters in 30.81 seconds in Ostrava--a world best in the distance. His only two 400 finals were in South Africa in March and April, and clearly rust busters: he only ran 48.47 and 46.28. Fred Kerley is currently the world leader with his NCAA record 43.70 from the West Prelims. Can Van Niekerk match that right now? Will he?