Sky Sports analyses the main contenders who could end Usain Bolt's hopes of a third consecutive Olympic gold medal in the men's 100m.
With the Olympics track and field events underway and the men's 100m once again expected to capture the headlines and the flash bulbs, we profile the men aiming to stop Bolt and become the fastest man in the world.
Bolt has won the 100m, 200m and 4x100m in each of the past two Olympic Games and barring injury or an unprecedented loss of form will be on the start line for the 2016 100m final at 2.40am on Monday morning - but who could be alongside him in the blocks?
The main contenders
Justin Gatlin
As the oldest competitor in the 100m, Gatlin will be looking to emulate his 2004 Olympic success in Athens where he won gold. The Rio Olympics will be the first time Gatlin and Bolt have met since the latter's victory by just ten milliseconds and, on that evidence, it's hard to call who will emerge triumphant this time.
Gatlin, whose 100m personal best stands at 9.74sec, is yet to run quicker than 9.80sec this year after consistently registering in the 9.70s bracket during 2015. That said, a 100m time of 9.80sec at the US Olympic trials was enough to secure the American a place at his third Olympic Games.
As well as the 100m discipline, Gatlin is a two-time World Indoor Champion in the 60-metre dash with victories in 2003 in Birmingham and 2012 in Istanbul, where he finished both races in 6.46sec.
Yohan Blake
Blake holds the accolade of being the second fastest man in history, behind Bolt, in both the 100m and 200m sprints. The 26-year-old boasts a personal best of 19.26sec in the 200m and 9.69m, tying him with America's Tyson Gray in the 100m.
Blake won individual gold in the 100m at the 2011 World Championships in a race which made him the youngest world champion at the distance, breaking the 10sec barrier at the tender age of 19 years and 196 days. And after winning three medals at his first Olympic Games in London, Blake was nicknamed 'The Beast' by fans across the globe, clinching silver in the 100m and 200m races along with gold in the 4x100m relay.
At the Jamaican Senior Trials in July, Blake clocked 9.95sec to win the 100m as he took full advantage of reigning champion Bolt's absence through injury.
But with Bolt back in the frame for Rio 2016, will Blake be able to eclipse his achievements at London 2012 by taking individual gold this time?
Trayvon Bromell
At 21-years-old, Bromell is among the youngest of the 100m competitors and is preparing to compete in his first Olympic Games. The American was on top form at the US trials to qualify for a place at Rio by equalling his personal best of 9.84 seconds, just behind Gatlin who won in 9.80.
Bromell is the first athlete under the age of 20 to break 10 seconds, clocking 9.97 in the NCAA Men's Outdoor Track and Field Championship final in June 2014. And while he may be relatively inexperienced on the global stage, it is safe to say Bromell is sure to be one to watch in the 100m heats this summer.
As for the Brits...
James Ellington
Ellington may be better known as a 200m specialist, but that didn't stop him securing a spot in Rio's 100m event when he recorded a time of 9.96 seconds at the British Championships in June. The 30-year-old Londoner memorably put himself up for auction on eBay before London 2012 in a bid to strengthen his chances of participating in the Games.
Ellington's dream of competing in the Olympics was realised thanks to the help of funding from a male grooming company; however there was no fairy-tale ending for the athlete who finished sixth in the 200m heats.
After his London 2012 disappointment Ellington's fortunes improved, winning a bronze medal as part of Great Britain's 4x100m relay team at the IAAF World Relays in 2014. Ellington went on to play a part in Great Britain's success at the Anniversary Games in July, storming to a world-leading time of 37.78 seconds in the 4x100m.
So, as Ellington gears up to compete in the 100m at Rio, will the team success he's enjoyed recently inspire him to individual triumph against the odds?
James Dasaolu
With a personal best of 9.91 seconds, 28-year old Dasaolu is the second fastest 100m runner in British history, behind Barcelona 1992 gold medallist Linford Christie who leads the way with 9.87.
Dasaolu, who took up competitive sprinting at the age of 18, achieved the national record in 2013 at the British trials in Birmingham before going on to be crowned European champion the following summer.
But it's not been all plain sailing for the Brit with 2015 a year to forget as he finished the season joint 71st in the global rankings, crashing out in his World Championships heats and consequently being axed from British Athletics' funding.
However, Dasaolu went on to redouble his efforts, embarking on a seven-week winter training camp in Doha in a bid to improve his results; and those efforts certainly reaped rewards as he crossed the line in 9.93 seconds to win the 100m at the British Championships in June.
CJ Ujah
Ujah became the youngest British sprinter to break the 10 second mark in the 100m when he ran a personal best of 9.96 seconds at the BFK Games in June 2014, just three months after turning 20.
Since then the 21-year-old training partner of Greg Rutherford has continued to thrive, reaching the 100m semi-finals at the 2015 IAAF World Championships with a time of 10.5 seconds in what was the fifth fastest of his career.
The national Under-23 record holder equalled his personal best in style when he crossed the line 0.09 seconds behind Usain Bolt in the 100m final of July's London Anniversary Games, standing him in good stead ahead of his first Olympic Games.
And while Ujah's odds of taking gold appear to be slim, as one of only five British men to run under 10 seconds he will be looking to continue to impress on the global stage.
The outsiders?
Andre de Grasse
Ontario born De Grasse will be looking to capitalise on an impressive display at the Canadian Olympic trials, as the 21-year-old prepares to compete in his first Olympic Games. De Grasse dipped below the 10 second mark for the first time this season en route to winning the 100m with a time of 9.99 seconds to his secure a place at Rio.
The double Pan American Games champion has also enjoyed great success in the 200m, holding the current Canadian record with a time of 19.88 seconds.
Jimmy Vicaut
France's Vicaut holds the European 100m record, with a personal best of 9.86 seconds. The 24-year-old helped the French 4x100m relay team take gold at the 2010 European Athletics Championships in Barcelona, as well as becoming only the second junior to run in a World Championship 100m in 2011.
It was in 2015 that the Frenchman set his fastest time, equalling the European 100m record previously set by Portugal's Francis Obikwelu at the 2004 Olympic Games in Athens. What's more, Vicaut has already had a taste of Olympic success helping the national relay quartet to bronze at London 2012 - but can he improve on that in Brazil?
Nickel Ashmeade
Two-time Jamaican world champion Ashmeade, who specialises in both the 100m and 200m sprint, has amassed a plethora of medals since first competing at junior level in 2006.
The 26-year-old boasts a personal best of 9.90 seconds in the 100m and secured his first 100m victory with gold at the 2006 Central American and Caribbean Junior Championships before turning his attention to the 200m, taking silver at the 2008 World Junior Championships.
Ashmeade, a high school team-mate of Yohan Blake, narrowly missed out on competing at London 2012 before storming to 4x100m relay victory with Bolt, Kemar Bailey-Cole and Nesta Carter a year later at the IAAF World Championships.
With Jamaica's 4x100m relay team odds-favourites to retain their Olympic gold title, Ashmeade will be hoping to clinch both individual and group success.