One of the highlights of watching the Olympics is seeing world records tumble. It doesn't happen all that often, only four were broken in London, with five in Beijing in 2008.
There was a 33-year-old world record broken in the women's 100m hurdles by Kendra Harrison before the games happened - and Harrison didn't even qualify for Rio. Here are the most likely candidates to break a world record in athletics and swimming, with a few mentions for some outsiders.
We begin with three candidates in athletics, and some outside chances.
1. Caster Semenya - Women's 800m
Current world record: 1.53.28 - Jarmila Kratochvilova (1983)
The South African burst onto the scene at the World Championships in 2009, absolutely destroying the field. It was subsequently revealed that she naturally produced three times the amount of testosterone in her body. The IAAF ruled that Semenya had to take testosterone regulating drugs in order to compete which has meant she hasn't been as dominant.
But, in 2015, the court of arbitration for sport ruled that the IAAF can't enforce athletes to regulate their testosterone levels.
What that means is that Semenya's form in 2016 has been back to her dominating form. She's won every 800m race she's been in this year, and was cruising when she crossed the line in 1.55 in July.
She's the overwhelming 2/17 (89.5%) favourite to win the race, and she'll only be racing herself to see if she can break the 33-year-old record.
2. Anita Wlodarczyk - Hammer
Current world record: 81.08m - Anita Wlodarcyck (2015)
In Rio, Poland's Wlodarcyck will essentially be competing against herself as she tries to better her own 2014 world record. The Pole owns the seven best women's hammer throws of all time, and only one other woman has thrown over 79 metres - Wlodarcyzk has done it all of those seven times.
Wlodarcyzk has thrown over 80 metres this year as well, and is the 1/9 (90%) favourite for the hammer gold - which she didn't claim in London.
3. Ashton Eaton - Decathlon
Current world record: 9,045 - Ashton Eaton (2015)
Ashton Eaton owns Decathlon. The American broke the 11-year-old world record in 2012, and then bettered his own record last year in Beijing.
He's so dominant in decathlon that even in this injury hampered season - his 8,750 score is world leading this year by a huge 145 points.
Eaton himself isn't concerned with other athletes - he just wants to get over 9,000 every time. If he's fit - his record is under threat in what should be his last Olympics.
Outside Chances:
There are a number of possibilities for some records to tumble. The men's 400 metres has a small chance if LaShawn Merritt, Kirani James, and Wayde van Niekerk come flying out of the blocks. Both the 1,500 metres for men and the 5,000m female events have had runners get close to the mark this year - with Asbel Kiprop and Almaz Ayana the most likely to break the marks.
Swimming is a little different to the old records in athletics. A lot of the swimming world records are very new. That's because of the supersuit that was popular in 2008 and 2009, before the FINA deemed them illegal in 2010. Since most of the records would have been broken with the advantageous supersuits, not many records are under threat. But there are some chances.
Here are the two best chances for a world record in swimming.
1. Katie Ledecky - 400m & 800m freestyle
Current world record: 400m = 3.58.37 - Katie Ledecky (2014), 800m = 8.06.68 - Katie Ledecky (2016)
Katie Ledecky owns the 400m and 800m freestyle. She's broken her own records multiple times - lowering the 800m mark by a whole seven seconds from 2013 to just January this year, when she posted eight minutes and six seconds. And she's only 19-years-old.
The nearest time to Ledecky in 2016 is 12 seconds behind. Meaning that al Ledecky has to do is turn up to collect the gold.
Her teammate Maya DiRado says of Ledecky:
Her off days are winning by a lot but not setting the world record. It's a totally different standard than everybody else is working on.
Ledecky is going to be one of the superstars of this Olympics.
2. Cate Campbell - 100m freestyle
Current world record: 52.06 - Cate Campbell (2016)
The 24-year-old claimed the world record just last month, shaving a second off the previous time which was achieved by Britta Steffen in a super-suit. It shows that Campbell is in great form, but she's got a lot of competition to win that will push her on too.
Her sister Bronte has a fantastic time this year too, and Sarah Sjostrom - who will be gunning for the 100m butterfly world record will push hard.
Other Chances:
In the men's events there are three swimmers who have the best chances - Sun Yang in freestyle, Mitch Larkin in the backstroke, and Adam Peaty. All three are young swimmers at the top of their game, but the records are ambitiously out there. Peaty is just a second away from the time, and has the best chance.
As mentioned earlier, Sarah Sjostrom is only a second away from the 100m butterfly time, Emily Seebohm is the big favourite in backstroke, and Katinka Hosszu will finish several seconds ahead of everyone in the 200m individual medley, but the world record time might just be beyond her.
See Also: Predicting How Every Irish Olympian Will Fare At Rio 2016
Picture credit: Stephen McCarthy / SPORTSFILE
