Usain Bolt achieved sprinting immortality last night, as he won his third Olympic 200m crown, after also winning gold in the 100m earlier in the week. However with the Jamaican confirming this will be his last Games, the men's 4x100m relay final tonight will be his last race at an Olympics.
The relay isn't just about him though, with the rest of the Jamaican team eager to emulate the success of four years ago in London. Their challenge will be much tougher in Rio, with the USA looking strong, and the Japanese coming out of nowhere in the heats to show they are real medal contenders.
Bolt's Olympic swan song
For the great man, this will be his last chance at an Olympic gold medal, and it will be his opportunity to claim the triple triple crown. He's won gold in the 100m and 200m three times in a row, in Beijing, London and now Rio de Janeiro, and all that's left now is to claim his third sprint relay gold in Brazil.
It would be the ultimate Olympic send off for Bolt, who is still hoping to compete at next year's World Championships, even if it's just the 100m he takes part in.
Jamaica's task will be one of their toughest yet, but they have a lot to live up to after what they achieved at London 2012 with a team containing Nesta Carter, Michael Frater, an in-form Yohan Blake and of course Bolt.
In 2012, the Jamaican team were pretty much level with the US going into the final 200m, but Blake passed Tyson Gay before handing to Bolt where the rest was history. The previous world record was 37.04 seconds; it was now 36.84.
It was a breathtaking display from the Jamaican's but it will take something very special for them to replicate that sort of performance in Rio tonight.
Because of Bolt, you would still have to make them favourites ahead of the rest of the field, but this relay has the potential to be an incredibly tight race right to the end.
The Jamaican's may play around with the order a little bit though with Jevaughn Minzie likely to miss out. That however would mean a different lead-off and there are also questions over whether Blake will get a place in the quartet too.
The message for the Jamaican runners will be simple; successfully get it round to Bolt on the anchor leg, and then believe in the legend once more.
Strong American's
The USA came out of the heats yesterday with the fastest relay time in the world this year, a 37.65. Therefore they will have great confidence that they can take the Jamaican's all the way and win the gold medal in what is a very strong team.
They were hugely impressive in the heats, and that was even without Justin Gatlin who was rested after the 100m, despite not making the 200m final last night. Therefore they could run even quicker with him coming into the quartet for tonight. Jamaica beware.
Gatlin ran the second leg of the relay at the 2012 games, before passing on to Gay who can always be relied upon to run a good bend, as he did in the heats. It is expected that Gatlin will again run that second leg, and that would mean he is likely to replace Christian Coleman in the quartet, with Mike Rodgers on the lead-off and Jarrion Lawson on the anchor again.
The USA will without doubt be the biggest threat to Jamaica as they try to retain their Olympic sprint relay crown, but this will be the year where the US could well run Bolt and co as close as they have done for numerous championships.
Both team's know what do when it comes to the biggest stage and the most pressurising finals, so it has all the makings of a cracking race.
Can Japan spring a surprise?
The surprise package from the heats yesterday morning were the Japanse quartet who had been rumoured to look good in training and then displayed that by pulling off a brilliant race to win their heat ahead of Jamaica.
They smashed their own national record with a time of 37.68 seconds to bring hope that they could well come away with a medal in the final tonight. All of their transitions were smooth and there wasn't an inch of trouble as they qualified as one of the quickest teams.
Everything about their race was seamless, and they'll be hoping that the baton changes go according to plan as they look to cause a potential upset. Jamaica and the US will probably have too much for them, especially with Bolt and Gatlin coming into the fray, but a bronze medal wouldn't be a huge surprise.
Considering how well the four of Japan's athletes ran in the heats, then it's unlikely they'll change who runs in the final as they look to set another national record. Aska Cambridge ran a brilliant anchor leg in the heats and will therefore be the man in charge of bringing the baton home in what could be a medal winning run tonight.
Meanwhile former World junior bronze medallist Yoshihide Kiryu will run the second bend which he was excellent at yesterday, after Ryota Yamagata and Shota Iizuka have run the opening two legs.
The rest of the pack
Great Britain before the heats would perhaps have been expected to be up there challenging for the bronze medal behind Jamaica and the US. Indeed they may still be, but after their run yesterday morning, they will have to improve massively going into tonight's final.
Like the majority of the other nations they have other men to bring into the quartet, with James Dasaolu likely to come in for one of the runners. Perhaps the most unconvincing performer from the heats was James Ellington and he may well be the athlete to sit out the final.
Richard Kilty and Harry Aikines-Aryeetey on the first two legs looked comfortable but over the final 200m they'll have to be a lot smoother if they're to give whoever is on the anchor a chance of crossing the line with a medal.
Canada qualified for the final with the fourth quickest time, and they have new silver and bronze medallist from the 200m and 100m, Andre De Grasse, to come into the quartet, so they could be in with a decent shout of winning a medal.
The 21-year-old has come out of nowhere in the past year and he'll be looking for his third medal of the games. It will be tough for the Canadian's, but behind the US and Jamaica the bronze medal could go to anyone.
Trinidad & Tobago could also be dark horses after they finished very strongly on the home straight to beat Great Britain to an automatic place in tonight's final with a time of 37.96 seconds. They aren't running as strong as they could be though, and with faster runners to come into the teams they'll be competing against, they could actually find matters quite tough.
The hosts Brazil also made it through, albeit as one of the fastest losers, and they are likely to be one of the back markers of this race. They do have Olympic pedigree in this event though, winning bronze in Atlanta in 1996 and then silver in Sydney at the start of the millennium. This race should be too much for them in terms of a medal hope though.
The final quartet making up tonight's relay final will be China, who finished with the third fastest time from the heats to prove that they're no slouches. They had a quicker time than Jamaica which was impressive, but like Brazil they aren't expected to be up there with the medal favourites come the final.
The script is firmly written then for Bolt to take the triple triple crown tonight, but it will be down to the ensemble cast to get the baton round, and then let the protagonist have the limelight one last time on the Olympic stage.