Double European champion Mo Farah is in action as athletes try to cement a place in the Great Britain and Northern Ireland team for the World Championships in Daegu next month, on the final day of the trials in Birmingham.
Britain can take up to three athletes in each event. The top two athletes in each event this weekend will guarantee their ticket to Korea, provided they have the 'A' standard qualifying mark.
The third spot in each event is discretionary and current form will be taken into consideration before a final selection is made after next weekend's Diamond League meeting in London.
Here are some of the expected final-day highlights:
SUNDAY (all times BST)
1512: Men's discus final
The discus will enjoy a rare moment in the spotlight courtesy of the emergence of world-class prospect Lawrence Okoye.
The 19-year-old, who until this year had focused on rugby, announced himself to the athletics world earlier this month with a 67.63m throw in Barnet - a British record bettered by only three throwers in the world this year.
European Under-23 champion Okoye, who has deferred his law degree at Oxford, will need to put up a strong defence to win the national title. Three other British athletes have achieved the qualifying standard, including 22-year-old Brett Morse, who improved to 66.06m at a meeting in Sweden on Wednesday.
1740: Women's pole vault
Teenager Holly Bleasdale did not even win the UK junior title last year, but has since raised the bar to emerge as a contender for a World Championships medal. She broke the British women's record by 10cm at the beginning of the month; her clearance of 4.70m in Germany ranks her joint fourth in the world this year. The 19-year-old has since become the European Under-23 champion.
Nonetheless, Bleasdale can expect to be pushed hard by former British record holder Kate Dennison, who improved her personal best to 4.61m in Barcelona last weekend.
1822: Men's 5000m final
Mo Farah has risen to world number one over both 5000m and 10,000m, vindicating his decision to move to the USA earlier this year to work under coach Alberto Salazar. Farah recorded his eighth successive victory last weekend when he set a British record in the 5000m of 12:53.11 - five seconds quicker than his previous best.
He should be untroubled in his attempt to win the national 5000m title for the first time since 2007. His nearest challenger, Andy Vernon, has a best of 13:27.85.
1936: Women's 800m final
Jenny Meadows has medalled at each of her last four major championships and yet she is still seeking her first national outdoor 800m title. That should change this weekend, as she is the only British athlete to dip under two minutes this year.
Several athletes are close to the 'A' qualifying standard of 1:59.80, led by Emma Jackson. She set a lifetime best of 2:00.24 in May and was just outside that time in her last race. Marilyn Okoro and Lynsey Sharp should also be pushing for a place at the World Championships.
1947: Men's 400m final
The last race of the weekend is likely to be a desperate scramble for selection as, surprisingly, no British athlete has achieved the 'A' qualifying standard of 45.25 seconds so far. For the first time, there is the prospect of a World Championships with no British male individual 400m runners.
European silver medallist Michael Bingham leads the way with a season's best of 45.42 seconds dating back to 11 June. He has not come close to that time in two subsequent outings. Olympic finalist Martyn Rooney has also struggled for form but he did set a season's best of 45.63 seconds last week, putting him third in the British standings behind Bingham and Luke Lennon-Ford (45.56 seconds).
Full timetable here (external link)