1. The World U20 Best In The 4x800 From 800m United

You can't do much better than a World U20 best. 

The best time in history ... by any girls indoor 4x800 team ever.

The team of Roisin Willis, Juliette Whittaker, Bailey Goggans and Sophia Gorriaran posted a time of 8:37.20, which broke the previous 30-year-old record time of 8:37.71 by less than a second. 

Hard to say much else. It was simply unmatched.