The IAAF World Indoor Championships are going down this week in Birmingham, England. The FloTrack crew will be on-site to provide updates and coverage of your favorite Team USA athletes, but for now let's check out the top storylines for the women's distance events.

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Women's 1500/3K: Who Will Best Pull Off The Popular Double?

Final (3K): March 1, 20:15 local time

First Round (1500m): March 2, 19:48 local time

Final (1500m): March 3, 20:39 local time

Notable Entrants (1500m): Genzebe Dibaba, Sifan Hassan, Laura Muir, Dawit Seyaum (probable), Beatrice Chepkoech, Shelby Houlihan, Colleen Quigley, Eilish McColgan

Notable Entrants (3K): Genzebe Dibaba, Hellen Obiri, Sifan Hassan, Laura Muir, Konstanze Klosterhalfen, Shelby Houlihan, Katie Mackey, Eilish McColgan, Fantu Worku (probable)

Analysis: The defending IAAF world indoor champions from 2016 in the women's 1500m and 3K are back in Sifan Hassan of the Netherlands, who has since then joined the Nike Oregon Project, and Genzebe Dibaba of Ethiopia, the world record holder whose coach Jama Aden was later that year picked up in a doping raid.

Hassan, it should be noted, is also a native of Ethiopia, and in 2018 the countrywomen will contest both events in Birmingham. There's no major global championship outdoors this year, so why not go for ultimate glory with the double?

Dibaba should certainly be considered the greatest indoor middle-distance runner of all time, as she owns three world indoor golds and six indoor world records over 1500m (3:55.17, 2014), mile (4:13.31, 2016), 2K (5:23.75, 2017), 3K (8:16.60, 2014), two miles (9:00.48, 2014), and 5K (14:18.86, 2015). 

But which Dibaba will show up this weekend?

After a superb 2016 that saw her win world indoor gold over 3K and Olympic silver over 1500m, the Ethiopian stumbled through the 2017 IAAF World Championships, placing dead last (12th) in the 1500m final and failing to start the 5K.

No matter how impressive her results are so far this season (her 3:57 season best is the third-fastest indoor mark of all time, and no woman has run faster indoors than Dibaba herself), there's no escaping the stain of failing to perform at last year's global championship. She is not unbeatable.

Hassan fared a bit better at worlds last summer, capturing fifth place in a wild 1500m kicker's final and earning bronze in the 5K. 

That 5K race was captured convincingly by Hellen Obiri of Kenya, the Olympic silver medalist in the event. Obiri will race the 3K at world indoors this week for the first time since capturing gold in 2012.

Whoever is training Hellen Obiri should train all our middle and long distance athletes. That final kick is the truth. pic.twitter.com/9qHOz6iDWB

— Kenyan Facts ?? (@KResearcher) August 14, 2017

Obiri's outdoor 3K PB of 8:20.68 is also the second-fastest in history behind Dibaba's indoor world record, though that mark is from 2014.

Obiri is the top contender to displace Dibaba and Hassan in the 3K, though 21-year-old German Konstanze Klosterhalfen is also a fearless competitor and one to watch in the longer event after clocking a national record (solo!) of 8:36.01 this month. She's also run 4:04.00 for 1500m this season, but will not race the shorter event at world indoors.

Top candidates for medals in the 1500m include 21-year-old Dawit Seyaum of Ethiopia, the 2016 world indoor silver medalist, who won the New Balance Indoor Grand Prix 1500m in 4:04.38 — the fourth-fastest time in the world this year.

Beatrice Chepkoech of Kenya is also a potential 1500m medalist, having hammered the field at this week's IAAF World Indoor Tour in Glasgow with a 4:02.21 national record.

Beyond Dibaba and Hassan, another top athlete doubling is 24-year-old Brit Laura Muir, who will be looking for her first global championship medal after harrowingly close finishes the past three years. 

Muir certainly enjoyed a solid record indoors, earning double 1500m/3K gold at the European Indoor Championships in 2017. Muir is in top form this year as well, given her 800m world lead of 1:59.69, an indoor personal best. Her indoor 3K PB of 8:26.41 — set last year — is the third-fastest in the field behind Dibaba and Obiri. Don't forget that she has 3:55 wheels as well.

For American track fans, the Bowerman Track Club's Shelby Houlihan is also testing herself with the double. While the 25-year-old has certainly established herself this season as one of the top harriers stateside, she has yet to earn the international pedigree that the top women in these fields boast. 

She was 13th in world championships 5K last summer and 11th in the event at the Rio Olympic Games.

Still, the double U.S. indoor champion appears most untested this season. She made short work of the fields at USAs with a perfectly timed kick to win both the 1500m and 3K in Albuquerque, and her 8:36.01 season-best 3K is the third-fastest time in the world this year — not to mention, second-fastest in American history.

Prediction (1500m): 1. Dibaba 2. Muir 3. Chepkoech

Prediction (3K): 1. Obiri 3. Hassan 3. Dibaba