The men's 800-metre race promises to be a doozy.

There's Canada's Marco Arop, the reigning world champion. There's Algeria's Djamel Sedjati, the fastest man in the world this season. And there's Kenya's Emmanuel Wanyonyi, second-fastest to both Arop at worlds and Sedjati this season.

"People say the 800's like Russian roulette," said Canadian Paralympian Nate Riech, who holds the T38 world record in the distance.

"If you make two mistakes it's not like 100, the 400, where you almost can't really make a mistake and then you're really in trouble or you just have to send it. In the 800 you can make a mistake or two, but if you get boxed in or you're on the outside running in lane two or lane three, that can really hurt you with 100 metres to go. 

"And so I think that's the beautiful thing about the 800 because no one knows."

WATCH | Arop's pursuit of greatness:

Marco Arop chases greatness

From his training base in the deep American south, Canadian works to be the best 800-metre runner in the world.

The competition at the Paris Olympics is shaping up to be no different. Each of Arop, Sedjati and Wanyonyi bring their own strengths and weaknesses to the table, and they've all held the world lead at various points this season.

Arop, the 25-year-old who lives in Edmonton, enters the race somewhat under the radar. His world-leading time only stood for a few hours before Wanyonyi broke it in April.

But the Olympics provide a different test. Those times were recorded at a Diamond League event in July, where competitors race just once. At the Olympics, you must get through heats and semifinals before lining up for a medal.

"I think everyone sees these flashy fast times and to be honest with you, they're impressive, but at the end of the day, if you don't have the legs after two rounds then it doesn't really matter how fast you can run for one race," Riech said.

National record possibly required

The three rounds come in a span of four days, with Round 1 set for Wednesday at 5:10 a.m. ET before semifinals on Friday and the medal race on Saturday.

"A lot of people call the semifinal the final and the final the second final. Because if you're chill and then all of a sudden 100 metres to go and you think you'll have legs and you don't, then it's like, holy crap, I'm not in the final," Riech said.

Arop, on the other hand, ran times in the solid mid-1:43 range on back-to-back days at the Canadian championships in June. Moreover, they were both solo competitions, which makes posting peak times even tougher.

Still, Riech said an Olympic medal may require Arop to run a national-record time. Arop owns the current mark at 1:42.85 from his world-championship victory last summer in Eugene, Ore.

"I think [the key] for him is to really keep it as chill as possible and just honestly not even make yourself known," Riech said. "Like just sneak in, get those auto [qualifiers], and just keep on going because he's going to have to run a Canadian record in the final to win. I mean, I think he feels that, but I think if he executes, there should be no problem. He can do that for sure."

Marley Dickinson, an athletics journalist for Canadian Running, agreed that the Olympic format plays into Arop's favour.

"For him to have that confidence in his back pocket and his mind to be able to say OK, I can run 1:43 three times in a matter of five days, I think he definitely comes in as one of the favourites," Dickinson said.

WATCH | Arop joins CBC Sports' Athletics North:

Marco Arop is ready to rise to the occasion at his 2nd Olympics | Athletics North

Marco Arop has learned a thing or two since fading away in the semifinals of his first Olympic Games. Now older, wiser, and possessing the confidence of a world champion, he’s going for gold in the men’s 800m in Paris. His story and more in our recap of Day 4 at the Olympic & Paralympic Athletics Trials in Montreal.

Fierce foes

Whatever confidence Arop may have, however, likely does not compare to the 25-year-old Sedjati, who has David Rudisha's world-record time of 1:40.91 in his sights.

"I am now thinking of the world record. I hope to run it at the Olympic Games," Sedjati said in July.

Wanyonyi, 20, is also coming with something to prove after his previous defeats against both Arop and Sedjati.

He's also used to high competition after getting through Kenyan team trials.

"Their trials is not easy. It's like survival of the fittest for sure. I mean to even make that final in Kenya, I'm sure there's like eight guys that can run 1:44," Riech said. "And Marco comes from a country where he's the only one who can run 1:44 and faster. And so I think [Wanyonyi] definitely has a strength there, and obviously being from altitude is huge."

The event is also more than just a three-horse race. Riech listed Great Britain's Ben Pattison, American Bryce Hoppel and France's Gabriel Tual as other contenders.

It all sets up for what could be a classic showdown at the Stade de France in which multiple records could fall.

Whoever crosses the finish line first will have earned it.