The US system of selecting the first three past the post means that every year ends with someone unexpected making the cut, and someone expected not making it – and in Olympic year the feelings of elation and dismay are heightened.
Nowhere will the competitive pressure be greater at a venue which is hosting a third consecutive Olympic trial than in the women’s 100 metres hurdles, where the US have the top five performers this year.
Topping the rankings with 12.24sec – a time which only Bulgaria’s world record holder Yordanka Donkova has beaten with her 12.21 from 1988 – is 23-year-old Kendra Harrison, with 2013 world champion Brianna Rollins with 12.53, Jasmin Stowers 12.55, Sharika Nelvis 12.61 and Kristi Castlin 12.62 filling the next four positions.
Harrison is the only high hurdler to have beaten 12.50 this year, and she has done it four times.
It would be a major shock if she should fail to make the cut - but five into three does not go so some world-class talent is about to suffer a fall.
The women’s 400m is similarly rich in talent in the US, which currently has three of the top performers of the season – and that does not include world champion Allyson Felix, whose hopes of attempting a 200/400m double at Rio 2016 have been boosted by a timetable shift but diminished by a niggling ankle injury.
Courtney Okolo with 49.71, Quanera Hayes 49.91 and Francena McCorory 50.23 have already established their obvious form this season, so Felix, who has raced sparingly this season, has her work cut out.
Her task in the 200m is hardly less bracing as she faces Tori Bowie, currently the second fastest in 2016 with 21.99 behind the Netherlands’ world champion Dafne Schippers on 21.93.
Bowie will also be one to watch in the women’s 100m, where her winning time of 10.80 at the International Association of Athletics Federations (IAAF) Doha Diamond League meeting is the second fastest run so far this season behind the 10.78 African record set by the Ivory Coast’s Murielle Ahoure.
But US rival English Gardner is only 0.01 behind her in the 2016 standings.
Meanwhile, the men’s 100m will witness 20-year-old world indoor champion and world outdoor silver medallist Trayvon Bromell seeking to steer a course to Rio 2016 against a field that will be packed with swift racers of the calibre of world silver medallist Justin Gatlin, former world 100 and 200m champion Tyson Gay and rising talent Ameer Webb.
The men’s 800m has produced some classic drama at the US Olympic trials, notably in 2008 when Nick Symmonds defeated Andrew Wheating in an epic contest after both had produced stupendous finishing efforts.
This year could see a race of similar intensity between the maverick talent that is Boris Berian - who won the world indoor title in Eugene in March and has only recently been cleared to run in the trials after overthrowing an attempted ban imposed by former sponsors Nike – and 19-year-old student Donovan Brazier, who produced the third best time of 2016, 1min 43.55sec, in winning the National Collegiate title at Hayward Field on June 14.
Berian, despite not having raced recently during his clothing and shoe contract wrangle, is seen as favourite, and has a time of 1:44.20 to his credit this year.
But if Brazier can cope with the pressure, the heat could get intense…
In the men’s 1500m, Ben Blankenship will seek a Rio 2016 place having missed out on earning a spot at last year’s IAAF World Championships in Beijing by just 0.02 seconds.
He will have the world indoor champion Matt Centrowitz for company, along with London 2012 silver medallist Leonel Manzano.
There is another potentially compelling rivalry to be played out in the women’s 10,000m, where Molly Huddle – whose ill-timed celebration on the line lost her a medal in the World Championships last year – faces the woman who profited where she lost, Emily Infeld.
Huddle will also seek a Rio 2016 place in the 5,000m, where her season’s best of 14:48.14 leaves her well clear on paper from her nearest domestic challenger, Nicole Tully, who has clocked 15:04.08.
Tia Brooks has the best shot put so far of the US throwers with the 19.73 metres she achieved in winning at the Birmingham Diamond League meeting earlier this month.
Brooks also opened up the Diamond League season with a win in Doha.
By contrast, Michelle Carter has had a slow start to her outdoor season with a best so far of 18.72m.
But she is the US record holder with the 20.24m she set three years ago, and earlier this year she won World Indoor Championships gold medal in Portland.
The men’s shot should be competitive across an even larger range of competitors given that six US throwers are currently ranked in the world top 12.
But the man whose title it is to lose is surely world champion Joe Kovacs, the only putter in the world this year to better 22 metres, which he has done twice.
Christian Taylor should not have undue trouble qualifying to defend his Olympic triple jump title at Rio 2016 given he already has the best two efforts of the season so far to his credit – 17.76m and 17.59m.
Marquise Goodwin, the NFL wide receiver and kick returner who last season played for the Buffalo Bills, is showing similar signs of dominance in the men’s long jump this year, where he also has the top two efforts of 2016 with 8.45m and 8.42m.
London 2012 pole vault champion Jenn Suhr has had her season interrupted by injuries – but so too have her main domestic rivals Sandi Morris and Demi Payne.
So Suhr, who winner of the world indoor title in March, should clear the bar for Rio 2016.
The action is due to underway in nearby Salem today with the 20 kiometres race walks for men and women which have been brought forward because of the expected hot conditions.
The Trials are due to last until July 10.