It's time to duel.

At least that's the spirit embodied by Noah Lyles as he emerged victorious in the 100 at the U.S. Olympic track and field trials. Lyles, 26, qualified for the Paris Olympics where he will have the chance to earn the title of the fastest man in the world.

His secret weapon? Trading cards.

Yu-Gi-Oh! cards, to be exact. In two consecutive rounds leading to his win, Lyles pulled a Yu-Gi-Oh! card out of his bib and flashed it to the camera before the heat.

What's the story behind Lyles' new tradition? And why Yu-Gi-Oh! cards?

What is Yu-Gi-Oh!?

Yu-Gi-Oh! is a trading card game played around the world. Its origins were as a manga created by Kazuki Takahashi that tells the story of a teenager who comes to possess a magical relic of ancient Egypt that contains the spirit of a 5,000-year-old pharaoh. Eventually, the card game depicted in the manga became so popular with Japanese readers that it was turned into a physical trading card game in 1999. Yu-Gi-Oh! soon expanded worldwide with the release of cards in North America in 2002 followed by a dubbed anime, movies and video games that became wildly popular.

The card game, which is published by Konami, continues to release new cards and host tournaments around the world. Games held by two players are called "duels." The game consists of three basic types of cards – monsters, spells and traps – and the basic objective is to reduce your opponent's life points to zero. Each monster card has a unique attack and defense value, and many have powerful effects. The idea is to use your monsters to battle those of your opponent, dealing damage equal to the difference in attack value and clearing the way for direct attacks. Spell cards can help fortify monsters and deplete your opponent's resources, but some can also be used defensively. Trap cards can catch your opponent off guard and swing a duel's momentum back in your favor.

Yu-Gi-Oh! has introduced many new mechanics and types of monster cards in its 25-year history, making it a much more complex and strategic game than the original iteration. But the basic principles still apply.

Why did Lyles have Yu-Gi-Oh! cards at U.S. Olympic trials?

Lyles said a running bet with world champion shotputter Chase Ealey is the reason behind his new tradition, and it has to do with a love the two athletes share for anime.

If Lyles continues to draw Yu-Gi-Oh! cards before races, Ealey will wear the famous Rock Lee leg weights, inspired by the Naruto anime, during her finals.

"Me and Chase Ealey got something going on," Lyles said. "She said if I pull out Yu-Gi-Oh! cards each round, she’ll wear the Rock Lee weighted shoes and drop weights during her finals. So I've got to live up to my part of the deal so she lives up to her part of the deal."

What cards did Noah Lyles show at U.S. Olympic trials?

On the first day of competition, Lyles pulled out a Blue-Eyes White Dragon monster card. Arguably the franchise's most iconic card, Blue-Eyes White Dragon has the highest attack value of any normal monster in the game and was the signature monster used by the series' anti-hero, Seto Kaiba.

The card has been printed countless times in many different rarities over the years, but the first-edition print of the card from 2002 is highly sought by collectors and is very expensive. One listing on eBay has the card, which was graded a Gem Mint 10 by PSA, priced at $150,000.

The second card Lyles showed was Exodia the Forbidden One, a card arguably just as iconic as the Blue-Eyes White Dragon and the monster used to defeat Seto Kaiba by the series' protagonist Yugi Muto, who duels while being possessed by the spirit of an Egyptian pharaoh, in the pilot episode of the anime.

Exodia is not a strong monster in terms of its statistics – it has just 1000 attack points compared to the 3000 of Blue-Eyes – but its effect is unstoppable if applied. If you hold Exodia in your hand along with the four other necessary pieces – the right leg, left leg, right arm and right leg – you automatically win the duel.

First-edition copies of this card can also fetch a pretty penny, but it's unlikely these expensive versions were used by Lyles and stuffed into his bib.

"It depends which version you want," Lyles said of the cards. "Not all of them are expensive, some of them you can find for $15-30, some of them you can easily pay $500."

What cards could Lyles pull out next?

Lyles is scheduled to run the 200 on Thursday and is the prohibitive favorite in the event, so which Yu-Gi-Oh! card could he show next? Red-Eyes Black Dragon and Dark Magician are intriguing options. Both are iconic cards used by Yugi Muto and other characters in the anime.

But what about Paris? If Lyles wanted to save the best for last, he could bring the legendary Egyptian God cards to the Olympics. The three cards – Slifer the Sky Dragon, Obelisk the Tormentor and The Winged Dragon of Ra – are incredibly powerful effect monsters and play a significant role in the events of the anime.