Jordan Spieth was dressed head to toe in Under Armour at Augusta. Ezra Shaw/Getty Images Jordan Spieth won his first major championship on Sunday with his wire-to-wire domination at the Masters, but he wasn't the only big winner.

In January 2013, Under Armour made a 19-year-old Spieth the face of the company's fledgling golf wing. This past January, Under Armour scrapped the final two years of that deal and gave Spieth a new 10-year contract.

That's right. Under Armour, which barely had a presence in the golf world three years ago, now has one of the two best young golfers in the game locked up until 2025.

While we don't know how much Under Armour is paying Spieth — golf deals are often heavily incentive-based — it was a huge commitment for a young golfer who had yet to win a major. In terms of length alone, the 10-year deal matched the deal Rory McIlroy received to replace Tiger Woods as Nike's top golfer.

And Under Armour reportedly wanted to make it even longer.

When Spieth and Under Armour negotiated their first deal, the company initially talked about a 25-year contract, according to Darren Rovell of ESPN.

Of course Spieth was not an unknown commodity, having won the US Junior Amateur twice, and Under Armour still had to persuade the youngster to wear its logo head to toe. According to Rovell, UA had three things going for it.

The company promised to feature Spieth as an athlete and not just as a golfer: This appealed to Spieth "because he saw himself as athlete. He's good in almost every sport he tries." Under Armour does not make golf equipment: This "turned out to be a huge advantage for Under Armour, as Spieth didn't have to change equipment to make a deal (unlike Nike, Puma, or Adidas)." Hunter Mahan: "Of the four golfers that UA had under contract, the one who had the biggest deal, Hunter Mahan, was represented by Jay Danzi, who also represented Spieth."

Spieth has a bright future, and Under Armour is coming along for the ride. Phil Noble/Reuters

If Spieth seemed understated in celebrating the Masters, Kevin Plank, the CEO and founder of Under Armour, was not.

"Thanks to Jordan, our company grew up today," Plank told ESPN, gushing about the classic and clean look it had given Spieth to wear at the Masters. "He was like apple pie with a golf club. There was nothing more Americana than Jordan Spieth this weekend."

This last comment may have been an indirect shot at Nike, which has made a point in recent months of dressing its top athletes, including McIlroy, in very bright neon colors.

Nike's neon is so bright it actually reflects off of Rory McIlroy's face. Andrew Redington/Getty Images

And it did not take long for Under Armour to start cashing in its first golf major win and that Americana look.

Shortly after the tournament ended, this was the front page at UnderArmour.com.

So while some golf fans wait to see if Tiger will ever be back, it looks as if they have their next big rivalry in Rory versus Jordan. And the upstart apparel company that wants to take down Nike in golf and beyond just adds another intriguing layer.