When the Golden State Warriors take the court at home on Thursday night against the Cleveland Cavaliers in the first game of the NBA Finals, the crown jewel of Under Armour’s athlete roster will stare down the most prominent and highest paid active Nike athlete.

Whenever Nike (NKE), Under Armour (UA), and Adidas (ADDYY), the biggest three sports apparel brands, find themselves facing each other at a major sports event or championship—whether it’s an all-Nike school vs. an all-Under Armour school at the College Football Playoff National Championship, or a Nike-sponsored golfer vying with an Adidas-sponsored golfer at The Masters—sports business pundits love to hype the significance of the brand battle. But this year’s Finals is truly the ultimate example. It’s a team led by Nike’s top athlete, LeBron James, against a team led by Under Armour’s top athlete, Stephen Curry.

And it’s even more fitting than that. James has been Nike-sponsored for 13 years, since he was just 18 years old in 2003, and has played 13 seasons. He’s a veteran of the league, a sports endorsement king, and left his hometown city to win a couple rings with the Miami Heat, then returned and is desperate to win a title in Cleveland. Curry, on the other hand, has only been with Under Armour for three years and only been in the league seven seasons. He won an NBA title in his sixth season; it took James until his tenth. Their brand sponsors mirror their stories, as Under Armour, even at 20 years old, is still seen as an upstart underdog to 52-year-old Nike.

Curry, the star of the Warriors and the MVP of the NBA’s past two seasons, is so strongly a symbol of Under Armour at the moment that in a new Morgan Stanley report, analysts cite Curry and his signature basketball sneaker, the Curry 2 – which has outsold Nike’s signature Lebron James shoes – as one of three factors creating “a stiffer headwind for Nike than it has felt in years.” Morgan Stanley downgraded Nike’s stock.

Under Armour knows what it has in Curry. On the company’s first-quarter earnings call in April, CEO Kevin Plank praised Curry to no end. He joked that Under Armour’s revenue grew by 30% in the quarter because Curry's jersey number is 30. He raved that Curry is the reason Under Armour has won over "the hardcore basketball kid." On the call, he spoke Curry’s name 25 times. The company is so jacked up about the Curry signature sneaker line that it cannot wait to release the Curry 3 in the fall, so on July 1 it will put out the Curry 2.5, which Curry wore in the Warriors' historic 73rd win and will wear in the Finals.

Under Armour boasts a slew of top athletes, including Jordan Spieth, Tom Brady and Cam Newton, but Curry is Under Armour’s god. His deal with Under Armour is believed to be worth $20 million per year, a steal considering that Jay Sole, the same Morgan Stanley analyst who downgraded Nike stock today, has predicted Curry could end up being worth $14 billion to Under Armour. (Of course, one basketball player is no magic bullet; Under Armour cut its outlook this week because of Sports Authority’s closure. There’s little Curry can do about that.)

The irony is that Nike had Curry, but lost him. Curry signed a small sponsorship contract with Nike in 2009 when he entered the league. When his contract was set to expire at the end of 2013, his star was rising, but hadn’t yet exploded. He went in for a meeting with Nike and, as an ESPN story this year revealed, a Nike executive mispronounced his first name and the company showed him a PowerPoint presentation that had Kevin Durant’s name on it. Curry and his father Dell, a former NBA player, walked. Curry signed with Under Armour.

James, meanwhile, landed a “lifetime deal” with Nike last year. Such an agreement is virtually unheard of in sports endorsements. It will likely bring James nearly $1 billion from the Swoosh, which is also demonstrating a faith in his future marketability even beyond basketball, a la Michael Jordan, the only other Nike athlete thought to have a lifetime contract.

When the Thunder blew a 3-1 game lead to lose the series, Nike also lost its chance at a Finals in which all three of the biggest stars would have been Nike-sponsored: James, Kevin Durant, and Russell Westbrook. Instead, the attention will be on Curry, who at this point is a walking Under Armour advertisement, and his rematch against James and the Cavaliers. Expect to see both brands ramp up TV advertising around their two stars.

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Daniel Roberts is a writer at Yahoo Finance, covering sports business and technology. Follow him on Twitter at @readDanwrite.

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