We recap the semis of the men's 400, women's 200, and women's 400m hurdles.

The times were incredible on the lightning-fast Rio track as former Olympic champs Kirani James (silver in 43.76) and LaShawn Merritt (bronze in 43.85) were the only men who did not set an all-time best mark for place.

The Big Three have claimed every global title since 2008 and their matchup in Beijing last year produced the first race in history with three men under 44 seconds. Could they go faster this year - and challenge Michael Johnson's WR of 43.18?

James' time, run in 48-degree temps, was the second-fastest ever in the month of April, behind only Michael Johnson's 43.75 in 1997.

Some of the sprint fields are Olympic caliber, including the men's 400 (Merritt, James, Santos), the men's 110 hurdles (McLeod, Parchment, Merritt, Oliver) and women's 100 hurdles (Harper-Nelson, Rollins, Harrison). The mid-d action is very intriguing. Jenny Simpson races for the first time in 2016 as she Mary Cain, Brenda Martinez and Morgan Uceny are all in the women's 1500. And the men's 800 will features a clash between Boris Berian, Erik Sowinski and Clayton Murphy. Plus the field events feature a cool $1,500 payment for the best mark in each round in the  'Throw For The Dough' and 'Leap For Loot'.

Get up to speed as we span the track and field globe.

Three men broke 44.00 for the first time in history as former world champs LaShawn Merritt (43.65 PB) and Kirani James (43.78) had to settle for silver and bronze. Cuba's Yarisley Silva won the pole vault in dramatic fashion, while Justin Gatlin (19.87) and Usain Bolt (19.95) cruised through the 200 semis to set up a thrilling final on Thursday.

The US pro track season starts off with a bang tonight with Ajee Wilson, Brenda Martinez, Chanelle Price, and Alysia Montano racing for $20,000, plus Kirani James vs LaShawn Merritt for $20,000, Ashton Eaton vs the hurdlers, and more. Saturday Leo Manzano and Matt Centrowitz square off in the mile.

A highlight will be the addition of an elite women's 800 with Brenda Martinez and Ajee Wilson. Other top names competing include Renaud Lavillenie, Jenn Suhr, LaShawn Merritt vs Kirani James and a deep 110H and HJ competition.

The 5 big stories from Lausanne.

$50,000 was on the line in the track races and $25,000 in the field and we saw some stellar April action.